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=Anatomical And Physiological Studies On The Growth Of The Inner Ear Of The Albino Rat=
Tokujiro Wada
Wistar Institute Of Anatomy And Biology
MEMOIRS
OF
THE WISTAR INSTITUTE OF ANATOMY AND BIOLOGY
No. 10
ANATOMICAL AND PHYSIOLOGICAL STUDIES
ON THE GROWTH OF THE INNER EAR
OF THE ALBINO RAT
TOKUJIRO WADA
THE WISTAR INSTITUTE OF ANATOMY AND BIOLOGY
PUBLISHED BY
THE WISTAR INSTITUTE OF ANATOMY AND BIOLOGY
PHILADELPHIA
iflir
CONTENTS
Introduction 5
Material 6
Technique 6
I. On the growth of the cochlea 12
A. On the growth of the radial distance between the two spiral
ligaments 13
B. On the growth of the tympanic wall of the ductus cochlearis. . . 16
1. Membrana tectoria 28
2. Membrana basilaris 39
3. The radial distance between the habenula perforata and
the inner corner of the inner pillar cell at base 47
4. The radial distance between the habenula perforata and
the outer corner of the inner pillar cell (resp., the inner
corner of the outer pillar cell) at base 48
5. The radial basal breadth of the outer pillar cell (including
the outer pillar) 57
6. The radial distance between the habenula perforata and
the outer border of the foot of the outer pillar cell 63
7. The greatest height of the greater epithelial ridge (dem
grossen Epithelwulst Bottcher's s. Organon Kollikeri) resp.
of the inner supporting cells 63
8. The radial distance between the labium vestibulare and
the habenula perforata 68
9. The radial distance between the labium vestibulare and
the inner edge of the head of the inner pillar cell 71
10. Vertical distance from the membrana basilaris to the
summit of the pillar cells 75
11. The greatest height of the tunnel of Corti 77
12. The height of the papilla spiralis at the third series of the
outer hair cells 77
13. The greatest height of Hensen's supporting cells 83
14. The angle subtended b> the extension of the surface of
the lamina reticularis with the extended plane of the
membrana basilaris 84
15. Lengths of the inner and outer pillar cells 85
16. Inner and outer hair cells 94
17. Deiter's cells 109
18. Summary and discussion 116
C. On the growth of the largest nerve cells in the ganglion spirale . 124
observations 124
Discussion 136
Conclusions . ... 143
3 (,
4 CONTEN TS
II. Correlation between the inception of hearing and the growth of the
cochlea 145
Observation 146
Discussion 152
Conclusions 155
III. On the growth of the largest nerve cells in the ganglion vestibulare. . . 156
Material and technique 156
Observations 156
Discussion 165
Conclusions 168
Final summary 169
Literature cited . . . 171
ANATOMICAL AND PHYSIOLOGICAL STUDIES
ON THE GROWTH OF THE INNER EAR OF
THE ALBINO RAT
INTRODUCTION
Since Alphonse Corti, in 1851, published his famous work on
the cochlea of mammals, studies on this organ have been made
by many authors and have produced fairly concordant results.
Concerning the postnatal growth of the internal ear, however,
systematic studies are lacking. Especially is there no investi-
gation, so far as I know, on the growth of the nerve cells in the
ganglion spiral, not even in the great work of Retzius. ('84).
It was the special object of these studies, therefore, to follow
the growth of the cells forming the spiral ganglion from birth
to maturity and to correlate the changes in them with the ap-
pearance of the functional responses and with the structural
changes in the membranous cochlea. In the course of this in-
vestigation studies were made also on the cells of the ganglion
vestibulare, in order to see whether these cells differed in their
growth from the cells in the spiral ganglion. Both of these
ganglia are situated in the course of nervus acusticus, but have,
as is well known, entirely different functions.
Thus determinations have been made on the diameters of the
cells of the ganglion spirale and of their nuclei at different ages;
of the nucleus-plasma ratios and of then* growth in relation to
those of other portions of the membranous cochlea. For the
cells of the vestibular ganglion similar determinations were also
made. Finally, these results have been compared with those
obtained from the study of other craniospinal ganglia in the
albino rat.
In presenting my results I shall begin with a description of
the changes in the larger portions of the membranous cochlea
and pass from these to the cell elements themselves, and then
to the observations on the ganglion cells and to the correlation
between hearing and the growth of the cochlea.
6 * ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
MATERIAL
For the present studies forty male and thirty female albino
rats were used, representing every phase of postnatal growth and
having approximately standard body weights. These were all
from the colony of The Wistar Institute, and were sometimes
from the same, and sometimes from different litters.
At first all these rats were tested for their ability to hear
and their equilibrium, and it was ascertained that after about
twelve days of age, or somewhat earlier, they responded posi-
tively to the test for hearing. Such examinations were deemed
necessary, to make certain that the rats used were normal.
I have arranged the animals thus tested in fourteen groups
according to age, each group having five individuals in it. Serial
sections from all these cochleas were made by methods to be
given later. Most of them were in the plane of the vertical
axis of the cochlea, but some were at right angles to it.
From the former I selected four ears in each group for the
study of the growth of the cochlea. For the study of the growth
of the ganglion vestibulare, I have used for the most part the
same specimens. For the study of the sections at right angles
to the vertical axis of the cochlea, sections from one ear of each
group were used.
TECHNIQUE
In order to obtain good preparations of this delicate organ,
the method of vital fixation (injection under anaesthesia) was
used. The method employed, and which proved almost ideal,
was that introduced by Metzner and Yoshii ('09), Siebenmann
and Yoshii ('08) and somewhat improved by Sato ('17). After
the animals had been tested to make sure that they were quite
normal, the fixing solution was injected through the aorta under
ether. The brain was then carefully removed, care being taken
not to drag the trunk of the nervus acusticus, as noted by Nager
('05), and the bulla tympanica was opened to allow the further
penetration of the fluid.
The bony labyrinth with its surrounding bones was then
placed in the fixing solution for two weeks, the fluid being re-
newed every day.
The fixing solution which I used consists, according to Yoshii
('09), of
10 per cent formol 74 parts
M tiller's fluid 24 parts
Glacial acetic acid 2 parts
According to Tadokoro and Watanabe ('20), this solution
is one of the best, ranking with that of Wittmaack ( '04, '06) and
that of Nakamura ('14).
This injection method is sometimes difficult to apply to very
young rats on account of the small size and the delicacy of the
vessels. When injection failed in very young animals, then
immediately the head was cut off and put directly in the fixing
fluid. Owing to the incomplete calcification of the very young
cochlea, the fixing solution enters rapidly and fixes the deep-
seated organs in good condition. Since the parts of the internal
ear are not yet well developed in the very young rats, they do
not suffer from this method of fixation as do the older cochleas.
Indeed, no differences are to be seen between the sections
prepared by vital fixation and by decapitation in very young rats.
For decalcification I have employed the following solution
during three days, renewing it every day.
Decalcifying fluid
5 per cent aqueous nitric acid 49 parts
10 per cent formol 49 parts
Glacial acetic acid 2 parts
After the specimens had been washed in running water for
three days, they were passed through the alcohols from 50 to 97
per cent. For the imbedding I have used 'parlodion' with good
results. Here it is to be mentioned that all the cochleas were
treated in the same way, even unossified cochlea being passed
through the decalcifying fluid, so that there should be absolutely
no differences in treatment.
8 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
The next important matter is the determination of the plane
of the section. For the measurement of growth changes it was
necessary to obtain corresponding sections from the several
cochleas. In an organ like that of Corti, which changes in its
details from one end to the other, however, it is very difficult
to accomplish this, but I believe that I have overcome most of
the difficulties.
After much testing, I found that a section parallel to the
under surface of os occipitale in the fronto-occipital direction
runs nearly exactly parallel to the axis of the modiolus of the
cochlea. In order to get the same direction from right to left,
I have taken as the standard the transverse plane of the under
surface of the os occipitale, controlling the direction of the section
with a magnifying glass. Thus nearly the same radial direction
and nearly corresponding places in the cochlea were obtained
in the several series of sections. This makes possible a trust-
worthy comparison of the measurements and drawings.
The cross-section of the cochlea was gotten by making the
plane of the cut transverse to the axis of the modiolus. To get
the corresponding levels is difficult. At first I divided all the
serial sections by 2^, which is the number of complete turns in
the cochlea of the albino rat. Next, from the number of the
slides representing each turn, I determined nearly the corres-
ponding level in the cochlea according to age.
All the sections were 10;x in thickness. The sections were
stained for the most part with haematoxylin and eosin, but
sometimes by Heidenhain's iron haematoxylin or the iron hae-
matoxylin and Van Gieson's stain. For the measurements,
however, only the sections stained with haematoxylin and eosin
were used.
For the examination of the larger parts of the cochlea and
their relations, the sections were projected on a sheet of paper
by the Leitz-Edinger projection apparatus, at a magnification
of exactly a hundred diameters, and the outline of the image
accurately traced. The remaining measurements of the ganglion
cells and the smaller portions of the cochlea were made directly
under the microscope. The measurements made on the tympanic
GROWTH OF THE INNER EAR OF ALBINO RAT 9
wall of the cochlea are somewhat complicated, but by the aid
of figures 1 and 2 they may be explained. In figure 1 lines 1-1,
1-1'. 2-2, 3-3 indicate, respectively, the height of the arch of
Corti, of the tunnel of Corti, of the papilla spiralis (Huschke) at
the third series of outer hair cells, and of Hensen's supporting
cells, respectively, above the plane of the membrana basilaris.
Lines 4-4' which are the extensions of the surface of the lamina
reticularis and of the membrana basilaris, subtend the angle 8.
To get the exact measurements of the radial breadth of the
membrana tectoria is very difficult, if not impossible, because it
is sinuous in its course; moreover, it differs in thickness from
point to point. Therefore, it has been variously described by
different authors. Intra vitam fixation tends to prevent dis-
tortion. We divide the membrana tectoria, figure 1, into two
portions, the first or inner (7-7'-9-9') and the second or outer
(5-5 '-7-7') or outer zones of Retzius; each of these is again
divided in two at 6-6' and 8-8', as shown in figure 1.
I have measured the radial distance of each portion and added
all four together. This total approximates the natural radial
breadth of this membrane, and since the sections have all been
prepared in the same way and examined by the same method, the
relations during growth can be followed.
In figure 2, 1-1 and 2-2, mark the length of the inner and outer
pillar cells, respectively, from base to the point, which is situated
just under their junction. It is to be noted here that the term
' pillar cell ' here applies to the pillars in the strict sense and does
not include the associated cells.
Distances 3 and 7 in figure 2 show the basal breadth of the
inner and outer pillars, respectively. The former is identical
with the distance between the habenula perforata and the outer
corner of the inner pillar after the inner corner of the pillar has
reached the habenula perforata, but there is some difference
between the two distances in very young rats. Distance 4 is
that between the habenula perforata and the inner corner of
the outer pillar; distance 5 is that between the habenula per-
forata and the outer corner of the outer pillar. The latter rep-
resents at the same time the radial breadth of the zona arcuata
of the membrana basilaris.
10 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
Fig. 1 Showing the localities for the measurement of each part of the tym-
panic wall of ductus cochlearis in the albino rat, 100 days old radial vertical
section. 1-1, height from the basal plane to the surface of pillar cells; 1-1',
greatest height of the tunnel of Corti; 2-2, height of papilla spiralis at the third
series of the outer hair cells; 3-3, height of Hensen's supporting cells; 4~4', 4
indicates the extension of the membrana basilaris and 4' the extension of the
lamina reticularis. The two lines subtend the angle 0. The radial breadth
of the membrana tectoria is taken as the sum of the four segments between the
lines 5-5' and 9-9'.
Fig. 2 Showing the method of measurement for several parts of the tym-
panic wall of the ductus cochlearis in the albino rat, 100 days old. 1-1, length
of inner pillar cell without head; 2-2, length of outer pillar cell without head
Distance 3 shows radial distance between habenula perforata and the outer
corner of inner pillar at base after twelve days of age this equals the radial basal
breadth of inner pillar. Distance 4, radial distance between habenula per-
forata and the inner corner of outer pillar at base. Distance 5, radial breadth
of the zona arcuata (Deiters') of membrana basilaris, and at the same time it
indicates radial distance between habenula perforata and the outer corner of
outer pillar at base. Distance 6, radial distance between the outer corner of
inner pillar and the inner corner of outer pillar at base. Distance 7, radial
basal breadth of outer pillar. Distance 8, radial distance between the habenula
perforata and outer corner of inner pillar cell at base. Distance 9, radial basal
breadth of the outer pillar cell. Distance 10, radial breadth of zona pectinata
of the membrana basilaris. Distance 11, radial breadth of entire membrana
basilaris.
Fig. 3 Showing the general outline of the cochlea in the radial vertical
section albino rat, 100 days of age.
ABBREVIATIONS
Line 1, 1, distance between two basal L.L.S., limbus laminae spiralis
spiral ligaments L.S., ligamentum spirale
Line 2, 2, distance between two apical L.S.O., lamina spiralis ossea
spiral ligaments M.T., membrana tectoria
7, first turn N.C., nervus cochlearis
II, second turn O., bone
///, third turn P.S., papilla spiralis
IV, fourth turn S., stria vascularis
D.C., ductus cochlearis S.T., scala tympani
G.S., ganglion spirale S.V., scala vestibuli
G.V., ganglion vestibulare
GROWTH OF THE INNER EAR OF ALBINO RAT
11
12 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
Distance 6 is that between the outer corner of the inner pillar
and the inner corner of the outer pillar. Distance 8 is that
between the habenula perforata and the outer corner of the inner
pillar cell. Distance 9 shows the radial basal breadth of the
outer pillar cell plus the outer pillar. Distance 11 shows the
radial breadth of the membrane basilaris comprising distance
5 (zona arcuata) and 10, which is the radial breadth of the zona
pectinata of the membrana basilaris.
ON THE GROWTH OF THE COCHLEA
As noted above, I have selected from at least seven serially
sectioned cochleas in each age group, four for this study, taking
one section in good condition from each labyrinth. From these
four sections the average values were taken for each age. Table 1
gives the data for the rats used here. As we see, sometimes two,
sometimes three animals were used at each age to get the four
best-prepared sections which corresponded. Determinations
accordingly to sex and side, therefore, cannot be based on like
numbers.
In the following text we shall often refer to the I, II, III and
IV turns of the cochlea. This calls for a word of explanation.
As the cochlea of the rat has nearly 2^ complete turns, four
cochlear canals are usually obtained in the radial vertical sections,
as prepared by me (fig. 3). Therefore, turn I does not mean the
first complete turn, but about the middle part of the basal
turn; turn II about the beginning of the middle turn; turn III
about the middle part of the middle turn, and turn IV about the
beginning of the apical turn of the cochlea. Usually the cochlea
has been divided for description by the authors into the first,
second, and third turns, or more definitely into the basal, middle,
and apical turns. For the purpose of this study, however, it
is desirable to adopt the divisions given above, because here
measurements are largely employed, and there are some differ-
ences in size, volume, and arrangement of structures, even between
the beginning and end of the same turn.
At all events, it is to be kept in mind that such divisions are
arbitrary, as the changes in the elements take place in a graded
manner.
GROWTH OF THE INNER EAR OF ALBINO RAT 13
A. On the growth of the radial distance between the two
spiral ligaments (fig. 3, 1-1, 2-2)
As we have usually four sections of the ductus cochlearis,
therefore four spiral ligaments in one radial vertical section,
there are two radial distances presented, the first, figure 3, 1-1,
connecting the two basal sections of the ductus on opposite
sides, and the second, figure 3, 2-2, connecting the two apical
TABLE 1
Data on the albino rats used for the study of the cochlea
AGE
BODY WEIGHT
BOOT LENGTH
BEX
SIDE
HEARING
days
grams
mm.
1
5.3
48
d"
R. L.
1
4.2
47
o"
R. L.
3
8.8
60
a"
R.
3
7.1
54
o"
R. L.
3
8.2
56
9
R.
6
10.2
64
9
R. L.
6
11.0
62
tf
R. L.
9
9.1
58
9
R. L.
9
9.8
57
tf
R. L.
=fc
12
13.0
70
a 1
L.
+
12
11.9
68
9
R. L.
+
12
14.8
72
d"
L.
+
15
13.0
74
0"
R.
+
15
13.5
75
9
R.
+
15
13.0
74
9
R. L.
+
20
30.0
96
cf
R. L.
+
20
28.0
94
c?
R. L.
+
25
38.4
107
9
R. L.
+
25
34.2
101
9
R. L.
+
50
60.0
128
9
R. L.
+
50
57.5
121
9
R. L.
+
100
145.6
176
a 1
L.
+
100
102.5
154
9
R.
+
100
100.5
152
9
R. L.
+
150
153.5
184
9
R.
+
150
188.9
191
d 1
R. L.
+
150
198.8
192
<?
R.
+
250
133.5
178
9
R. L.
+
263
140.3
171
9
R. L.
+
365
205.4
202
0"
L.
+
365
170.4
182
9
R. L.
+
368
179.0
196
9
R.
+
546
282.1
222
<?
R. L.
+
546
227.1
204
rf
R. L.
+
14
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
sections. These distances measure the radial breadth of the
membranous cochlea and of the modiolus combined at these levels.
In table 2 (chart 1) are entered the values for the radial
distances found between the two spiral ligaments in fourteen
TABLE 2
Radial distance between the two spiral ligaments in radial-vertical section
(chart 1, figure 3)
AVERAGE DISTANCE BETWEEN TURNS IN M
AGE
TTTT'nWP
I-II
III-IV
I-II plus III-IV
days
grams
mean
1
5
1410
925
1168
3
8
1560
1025
1S93
6
11
1650
1175
1413
9
10
1635
1225
1430
12
13
1640
1233
1437
15
13
1655
1235
1445
20
29
1645
1250
1448
25
36
1620
1250
1435
50
59
1615
1253
1434
100
112
1663
1270
1467
150
183
1618
1290
1454
257
137
1655
1275
1465
366
181
1635
1285
1460
546
255
1680
1265
1473
Ratios 1 12 days 1 1.2
1 20 " 1.2
1 546 " 1.3
TABLE 3 Condensed
Ratios of distances between the two spiral ligaments along 1-1 (turns I-II) and
along 2-2 (turns III-IV), figure 3
AGE
BODY WEIGHT
Ratios between the two distances
turns I-II and III-IV
days
grams
1
5
. 1:0.66
8
11
:0.72
18
21
:0.75
213
138
:0.77
age groups, from one to 546 days. As we see, the average value
of the two distances grows rapidly from birth till six days of
age. After that period the value increases gradually till twenty
days, while after twenty days the increase is very slight indeed.
The ratios between 1 and 12, 1 and 20, and 1 and 546 days show
these relations.
GROWTH OF THE INNER EAR OF ALBINO RAT
15
In table 3 are given the average ratios between two radial
distances between I-II and III-IV at four ages. Here we can also
see a rapid increase in the ratio from one to eight days of age,
while afterwards the ratios rise very gradually. The data in
table 2 show that at nine days the mean diameter of the bony
cochlea as thus measured is approximately 97 per cent of the
value at maturity. The cochlea thus attains nearly its full size
at an early age. Chart 1 illustrates this point.
IOUU
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Chart 1 The radial distance between the spiral ligaments, turns I-II and
III-IV, table 2, figure 3 (/-/) and (-).
Radial distance at turns I-II.
Radial distance at turns III-IV.
Average radial distance for the two foregoing measurements.
All the charts are plotted on age.
The scale for age changes at 50 days. From to 50 days one interval is
equal to five days. From 50 days on, one interval is equal to twenty-five days.
Unless otherwise stated, the measurements recorded in these charts have
been made on radial-vertical sections.
16 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
B. On the growth of the tympanic wall of the ductus cochkaris
Figures 4 to 12 show the appearance in outline at birth, at
three six, nine (not hearing), nine (hearing), twelve, twenty one
hundred, and 546 days, respectively. These figures have been
drawn from the best corresponding sections at the beginning
of the middle turn of the cochlea, figure 3, turn n, which I have
selected as the type, as did Retzius.
The fact, demonstrated by many authors, Bottcher ('69),
Retzius ('84), and others, that development progresses from
the basal to the apical turn is confirmed in the albino rat.
In the albino rat the development of the cochlea, and es-
pecially of the ductus cochlearis, is somewhat retarded as compared
with man, and the papilla with its elements developed in a great
measure during the first ten days after birth.
As we see in figure 4, the ductus cochlearis in the new-born
rat is very immature. It is remarkable that the space which
lies in adult rats axialward of the papilla spiralis between the
membrana tectoria and the limbus spiralis-sulcus spiralis internus
(fig. 10) is not yet to be seen. Instead of the space, there is the so-
called greater epithelial ridge (der grosse Epithelwulst of Bottcher)
figure 4, G. consisting of pseudostratified epithelial cells. These
long and narrow cells lie pressed very closely together with
their large oval nuclei at various heights. The surface of the
prominence sinks slightly in its center, and at the outer end of
the prominence more rapidly, where it passes over into the so-
called lesser epithelial ridge fig. 4, L. (der kleine Epithelwulst)
at an obtuse angle.
The latter is, of course, a relatively small prominence, making
up the greater part of the papilla spiralis. The pillar cells of
Corti lie with their upper ends at the most inner part of the
surface of the lesser ridge just in the angle with the greater
ridge. They form two entirely separate rows of cells, the inner
and the outer, but so close together that we cannot detect any
space between them. Only the protoplasm of the inner pillar
cell is more transparent above the nucleus, and on the inward
side there is a thin rod passing from the upper end to the lower
GROWTH OF THE INNER EAR OF ALBINO RAT 17
part near the base. This transparent area is not the locus of
the future tunnel of Corti, but marks the protoplasmic change
into the pillar, as the transparent substance condenses into the
rod. We can see this change beginning in the basal turn before
it appears in the apical turn of the cochlea. The inner and
outer cells make a triangle with a narrow base, which clings to
the membranea basilaris; they turn somewhat outward. 1
A large oval nucleus lies in the basal part of each cell; that of
the inner pillar cell is very large, about twice as large as that
of the outer, and with its long axis in a radial direction. As
figure 4 shows, the inner corner of the inner pillar cell does not
yet reach to the habenula perforata.
The hair cells, which in the albino rat are in four rows through
all the turns, are separated by the pillar cells into two groups,
the inner containing one and the outer three rows of cells. They
are comparatively well developed at birth (fig. 4). The inner
hair cell belongs to the greater ridge, as Kolliker ('67), Gottstein
(72), Retzius ('84), Held ('09), and others have already affirmed,
and contrary to the assertaion of Bottcher ('69) and others.
It is situated in the most outer part of the declivity of the
greater ridge and slants away from the axis with its round lower
end at about half the height of the greater thickening. It has
a large round nucleus in the base and the small hairlet at the top.
This hair cell is nearly twice as large as the outer hair cells.
The three outer hair cells reach down to the middle of the lesser
ridge, not through it, having no process at their basal end.
They end with their upper parts at the surface of the prominence.
They stand not straight, but turn with their long axis very
slightly inward, i.e., the in direction opposite to the long axis
of the inner hair cells. They are cylindrical in form with a round
nucleus at their base and small hairlet on the top.
Below the outer hair cells stand the three rows of Deiters'
cells, which have large oval nuclei. These rest with their wide
bases on the basilar membrane and their pointed ends reach
to the surface of the epithelium. They are retarded in develop-
1 In the following description of the cochlea, 'outward' means away from the
axis 'inward' towards the axis.
J8 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
ment, and at birth their cell bodies are short and undeveloped,
so that they hardly suggest the adult cells.
Hensen's supporting cells (fig. 10, at maturity) are as yet
undeveloped and nearly uniform in height, their nuclei being
at nearly the same level.
Outward from the Hensen's cells the height of the epithelial
cells at maturity rapidly diminishes and passes over to the
cylindrical cells of sulcus spiralis externus. At birth no such
distinction is present. Through all the turns the surface of the
lesser epithelial ridge remains about parallel to the plane of the
membrana basilaris.
The membrana basilaris, which stretches from the labium
tympanicum outward to the crista basilaris of the ligamentum
Figs. 4 to 12 Showing the increase in size and morphological changes in
each part of the tympanic wall of ductus cochlearis of the cochlea during
growth, in the radial vertical section albino rat. All the figures have been
uniformly enlarged.
Fig. 4 One day. C, greater epithelial ridge; L, lesser epithelial ridge.
Fig. 5 Three days.
Fig. 6 Six days.
Figs. 7 to 8 Showing the differences in size and morphological changes in
the tympanic wall of ductus cochlearis between a nine-day-old rat which can
already hear (fig. 8) and one that cannot (fig. 7)
Fig. 9 Twelve days.
Fig. 10 Twenty days. In figure 10 we have drawn all the elements of the
organ.
ABBREVIATIONS
M.T., membraua tectoria a. Corti O.P., outer pillar
L.V., labium vestibulare of crista B.C., basal cells
spiralis D.C., Deiters' cells
S.S.I., sulcus spiralis interims Bo.C., Boettcher's cells
S.I.C., cells of sulcus spiralis interims L.S., ligamentum spirale
I.S., inner supporting cells N.F., myelinated fibers of ramus
I.H., inner hair cells acustici
O.H., outer hair cells R.F., radial fibers of ramus basilaris
H.S., Hensen's supporting cells acustici in the tunnel of Corti
S.E.C., cells of sulcus spiralis externus T., tunnel of Corti
M.B., membrana basilaris B., blood vessels
I. P., inner pillar 0., bone
Fig. 1 1 One hundred days.
Fig. 12 546 days.
GROWTH OF THE INNER EAR OF ALBINO RAT 19
4
20
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
GROWTH OF THE INNER EAR OF ALBINO RAT
21
HS
22
spirale, consists of two layers, an upper, membrana basilaris
propria, and an under, tympanic investing layer (tympanale
Belegschicht : Retzius). The former, of course, is divided into
two portions, an inner, zona arcuata (Deiters) and an outer,
zona pectinata (Todd-Bowman). While the zona arcuata is
thin from the beginning of life, the zona pectinata thickens at
its central part where it contains cells with oblong nuclei. On
passing to the spiral ligament it again becomes thin. In the
young, the under layer is not so regular in structure as in the
adult. The *cells close to the basilaris propria are arranged
vertically.
On the contrary the cells below them, which vanish in great
part with age, have an irregular arrangement; those near the
endothelial cells of scala tympani having a more radial arrange-
ment. Therefore, this layer is thick, several times the thickness
of the basilaris propria, and the thickness increases towards
the upper turns. The vas spirale is strikingly large at this stage
and lies just under the outer pillar and the Dieters' cells.
The membrana tectoria, beginning at the inner angle of the
ductus cochlearis, where Reissner's membrane rises, covers the
epithelium of the limbus laminae spiralis and the greater epithelial
ridge, lying close to their surfaces. At the inner part it is thin,
but thickens where the greater ridge begins, and at the outer
part again becomes thin. In the basal turn there is seen as a very
thin strand reaching to Hensen's prominence, but in the apical
turn it reaches hardly to the inner hair cell. Although it gives
rise to several thread-like processes going to the surface of the
papilla, these do not seem to connect with the hairs of the hair
cells, but with the terminal plates of the Dieters' cells.
When we divide the tympanic wall of the ductus cochlearis at
the boundary between the greater and lesser epithelial ridges,
we observe that the inner portion from the inner angle to the
outer end of the greater ridge is far larger than the outer portion,
which, however, is the more important for hearing. This
relation becomes more evident as we pass from the base to the
apex. Moreover, the total radial length of the tympanic wall
GROWTH OF THE INNER EAR OF ALBINO RAT 23
diminishes at this stage towards the apex, though it is larger
in the beginning of the middle turn than in the middle of the
basal turn. As will be shown later, these relations are entirely
reversed in the adult cochlea. This fact indicates that the
cochlea at this stage is very immature.
In the three-day-old rat the cochlea is much better developed
(fig. 5). The radial breadth of the typmanic wall of the ductus
cochlearis becomes greater in all the turns, especially in the upper
turn; therefore the differences between the radial breadths in
each successive turn are smaller than at the earlier stage. There
is some change as we pass towards the apex in the relation of
the inner and outer portion of the tympanic wall. At the basal
turn and the beginning of the middle turn the radial breadth
of the outer portion increases greatly, but diminishes again
towards the apex. Although the radial breadth of the inner
portion increases through all the turns, the proportion of this
increase becomes greater towards the apex. As the inner portion
is composed of the greater epithelial ridge and of the limbus
laminae spiralis, and as the breadth of the latter diminishes
towards the apex, the increase of the radial breadth of the inner
portion is due to changes in the greater epithelial ridge.
The heights of the greater epithelial ridge, however, diminishes
through the successive turns, becoming less and less from base
to apex. Thus in the cochlea at this age it has a small radial
breadth and vertical height in the basal turn and a larger radial
breadth and height in the upper turns.
In all the turns the inner hair cell is inclined outwards and
lies with its surface forming the outermost part of the greater
ridge. The obtuse angle which it helps to make (fig. 5) as a
boundary between the greater and lesser ridge in upper turns,
vanishes in the basal turn where there is no sharp boundary
between the two ridges.
The pillar cells of Corti develop more and more during this
early stage; the radial breadth of their base increases, but as
yet there is no space between them. They incline much more
outwards than in the earlier stage. The protoplasmic change
in the rod progresses, especially in the basal turn, and the head
plate of the cell can be seen distinctly.
24 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
The outer hair cells become higher and wider; they are slightly
inclined inward in the upper turn. On passing towards the
basal turn the inclination inward increases, and in the basal
turn it is most oblique, almost at 45, to the plane of the basilar
membrane. In figure 4 the inclination of these cells is only
slight.
Deiters' and Hensen's cells are not well developed; the con-
ditions are as in the former stage.
The plane of the surface of the lesser epithelial ridge is inti-
mately related to the development of the outer hair cells and
Deiters' cells, and as the latter are in an undeveloped condition,
it runs nearly parallel to the plane of the membrana basilaris,
sometimes dipping outward.
The membrana basilaris seems to be much longer; its com-
position is about the same as that in the one-day rat, only the
thickness is somewhat decreased, owing to the reduction of the
rows of cells in the tympanic layer.
The membrana tectoria grows in breadth and thickness,
covering very closely the inner portion of the tympanic wall
and connects outwards with Deiters' and Hensen's cells by
slender fibrous processes the so-called outer marginal zone.
The hairs of the cells stand between these processes, but have
no connection with them.
The vas spirale does not suffer reduction.
At six days (fig. 6) the development of the cochlea has pro-
ceeded futher. The radial breadth of the tympanic wall has
increased. Thus we find the tympanic wall, especially its inner
portion, increasing towards the apex, chiefly owing to the aug-
mentation of the radial breadth of the greater ridge. In this a
remarkable change is to be seen. In the basal turn the long
slender cells disappear in the inner part of the greater ridge,
and instead of them there are found cylindrical cells with oval
nuclei near their bases.
The height of these cells increases gradually to the level of the
surface of the inner hah- cell; their upper surface is here in contact
with the membrana tectoria. Thus a space appears between
the cylindrical epithelium and the membrane the sulcus
GROWTH OF THE INNER EAR OF ALBINO RAT 25
spiralis interims which is deep and wide in the basal turn,
becomes gradually shallow and narrow as we pass upward, and
in the middle part of the middle turn is to be seen as a small
and flat space. In the apical turn it is not yet present. The
inner side of this space is made by the labium vestibulare of
the limbus laminae spiralis.
As a result of this change in the greater ridge, the obtuse angle
between the greater and lesser ridge vanishes entirely, and the
two surfaces come to lie in the same place. The inner hair cell
becomes larger and inclines less outward.
It is to be noted that the inner hair cell is supported on both
sides by long slender cells. These have been variously described
by several authors, but first Hans Held ('02) and afterwards
Kolmer ('07) have considered them as supporting cells, reaching
from the surface of the hair cell to the plane of the basilar
membrane. Held has termed the cell which lies outward the
' Phalangenzelle. '
I have paid some attention to this cell and the changes in it.
It is long and slender and stands between the inner hair cell
and the inner pillar cell, with the upper end reaching to the
surface, and is attached at its base to the inner corner of the
inner pillar. The oblong oval nucleus lies in its basal portion.
On the inner side of the inner hair cell there is a group of two to
three cells of the same kind. These cells, termed ' Grenzzellen '
by Held, stand near the habenula perforata, reach to the height
of epithelium, and have their bases in intimate relation to the
former.
These are not neuro-epithelial cells nor in intimate relation with
the nerve fibers, but similar to the Deiters' cells which support
the outer hair cells.
The developing pillar cells become progressively wider at their
bases. The inner pillar cell sends a long foot towards the habenula
perforata and in the basal turn it sometines reaches to it. The
outer pillar cell increases its length very rapidly and extends
its foot outward on the basilar membrane. Thus in the basal
turn the triangle made by the inner and outer pillar cells and
having a short base, in the upper turns changes to an equilateral
26 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
triangle and stands upright on the basilar membrane. In the
apical turn the inner pillar cell is not yet so long as in the lower,
turns and is still inclined outwards. The head plates and pillars
are fairly prominent, but there is as yet no space between them.
The outer hair cells have grown and are inclined inward.
Deiters' and Hensen's cells have not yet begun to develop, as
have the other elements of the organ of Corti just described.
In the membrana basilaris we see the reduction of cells in
the tympanic covering layer. The vas spirale shows more or
less reduction. The membrana tectoria increases its radial breadth
following the associated structures. The so-called marginal zone
connects with Hensen's cells and the lamina reticularis by
fibrous processes.
Among five nine-day-old rats, as shown later, one responded
to the tests for hearing. As the majority of them gave no re-
action, the cochlea of the latter, non-hearing rat, may be taken
as the type for this age. The differences between the cochlea
of the hearing and non-hearing rats will be mentioned later.
In rats of this age (fig. 7.) the cochlea is still further advanced.
The sulcus spiralis internus appears through all the coils, and is
deepest and broadest in the basal turn, diminishing in depth
or gradually toward the apex. The cells covering the space are
low and cuboid in the lower turns, but in the apical turn they are
yet relatively high, cylindrical cells.
These cells probably have their origin from the long slender
cells of the greater epithelial ridge, as Bottcher ('69) and others
maintain, although Gottstein (72) and some others think that
they come by the outward migration of the epithelium of the
limbus spiralis, and Retzius ('84) regards this latter view as the
more probable.
The inner and outer hair cells become large and approach
their mature form. The supporting cells of the inner hair cell
are very evident.
The pillar cells develop more and more, their radial breadth
increases and the pillars and headplates also become distinct.
Sometimes we see a small space between the inner and outer
pillar cells in the lower turn, but not in the upper. Nuel 's space
GROWTH OF THE INNER EAR OF ALBINO EAT 27
is not yet to be seen. Deiters' cells become longer, somewhat
in the processus phalangeus but chiefly in the cell body, and the
nuclei move upward. Hensen's cells also increase in height
slightly.
While the membrana tectoria lies close to the surface of the
outer part of the greater ridge in the upper turns of the cochlea,
there arises a small space between them, which is continuous with
the sulcus spiralis internus. The outer marginal zone of the
membrane is still connected with Hensen's supporting cells and
the lamina reticularis. The vas spirale remains as a large vessel.
This is the condition of the nine-day cochlea in a rat which does
not hear.
Although the detailed description of the cochlea of the nine-
day rat which can hear will be deferred for a time, yet to complete
the series of growth changes, figure 8, representing the cochlea
in such a rat, is inserted here.
In the next stage, twelve days old (fig. 9), the development of
the tympanic wall is much advanced. The cells lining the sulcus
spiralis internus and the-inner supporting cells have nearly their
mature form and arrangement in the basal and middle turns;
only in the apical turn many and slender cells remain close to
the inner hair cell.
The outer pillar cell shows a remarkable increase in length so
that it is twice as long as in the former stage, while the growth
of the inner pillar is much less marked.
Therefore the outer pillar is much longer than the inner
through all the turns. From this change in the pillar cells it
results that the nearly equilateral triangle formed by them
becomes unequal and its summit is shifted inward. In all the
turns we can see the tunnel of Corti and also the space of Nuel.
The hair cells develop further and their previous inclinations are
increased.
Deiters' cells show a very rapid development, especially in
the cell body, which increases many times, the nucleus moving
upwards. The inclination of these cells follows that of the
outer hair cells.
28 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
Hensen's supporting cells are also fully developed. Through
the development of Deiters' and Hensen's cells a change is
effected in the course of the lamina reticularis. It runs no longer
parallel to the plane of the membrana basilaris, but dips inward.
Though the membrana basilaris remains nearly stationary in
its breadth, the thickness of the tympanic covering layer is
reduced and the longitudinal nuclei in the zona pectinata diminish
in number.
The membrana tectoria reaches in the basal turn to the outer-
most row of the outer hair cells, but the apical turn only to the
second row. The so-called 'outer marginal zone' connects with
the terminal frame (Schlussrahmen) of the lamina reticularis.
In the next stage, the twenty-day-old rat (fig. 10), the papilla
spiralis and the tissues about it are developed almost com-
pletely; therefore, the structural relations of the cochlea accord
nearly with those of the adult cochlea, as generally recognized
in histology.
It is to be noted here that in the basal turn, Bottcher's cells
are to be seen in sulcus spiralis externus* as a cell group situated
on the outer part of the vestibular surface of the membrana
basilaris. This cell group consists of several granular compact
and sharply bounded cells entirely covered by high swollen cells
on all sides. That this cell group belongs to the epithelium of
the sulcus spiralis externus can be easily demonstrated. While
the cells in this group show no particular changes in structure,
the neighboring cells diminish in their height and size towards
the apex, and finally become similar to the former. After twenty
days of age the general features of the cochlea are those of the
adult and do not require general description. The finer differ-
ences will be discussed in subsequent chapters.
Figure 11 shows the relations at 100 days and figure 12 at
546 days.
1. Membrana tectoria. As stated above, this membrane is
divided into two zones, an outer and inner, using the outer edge
of the labium vestibulare as the point of division (fig. 1, 7-7').
Each zone was again divided into two equal parts at 6-6'and8-8'.
Thus the sum of the breadths of the two outer parts represents
GROWTH OF THE INNER EAR OP ALBINO RAT 29
in each instance the breadth of the outer zone, and the sum of
the two inner parts that of the inner zone, while the sum of all
four parts gives the total radial breadth. For the purpose of the
exact measurement of the growth of the membrane, I have,
as noted above, projected the sections at 100 diameters and made
the determinations on the outlines thus obtained.
In table 4 (charts 2 and 3) are given the values for the total
average breadth, as well as for that of each zone, and also the
thickness of the membrane, from 1 to 546 days of age. At the
bottom of each column are given the ratios of the breadth at
1 to 546, 12 to 546, and 20 to 546 days. While the ratio between
1 and 546 days is 1.7, those from 12 to 546 days and 20 to 546
days diminish to about 1:1.0, that is the membrane at twelve
days has attained about its full breadth, and there is only a
very gradual increase in its breadth with advancing age. After
twelve days similar ratios are found for the separate zones as
well.
From 1 to 546 days the ratios for the two zones differ con-
siderably; that for the second zone is 1:1.2 and that for the
first is 1:3.6. This is due to the fact that in the cochlea at birth
the development of the labium vestibulare is incomplete, even
in the basal turn, while at the apex we can very often hardly
see the invasion of the mesenchymal tissue in the inner part of
the greater epithelial ridge.
At every stage the outer zone is broader than the inner; the
ratio between them at birth is 1:3.8. This diminishes to 1:1.25
at twelve days, after which age it remains practically constant.
Owing to the form of the membrana tectoria and to its great
sensitiveness to the method of preparation, it is difficult to
obtain good values for its thickness.
Generally speaking, the membrane is thickest about midway
between the outer edge of the labium vestibulare and the inner
boundary of the inner hair cell, and it was here the measurements
given in table 4 were made. As shown in this table, the thickness
increases rather rapidly from birth to twenty days, but after
that period remains approximately constant.
30
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
As we know, the radial breadth of the membrane increases
gradually from the basal to the apical turn. Table 5 (charts 4,
5, and 6) shows how the breadth of the total and of each part
of the membrane changes in successive turns from base to apex
according to age. At birth it is broadest in the beginning of the
middle turn (turn II) decreasing gradually towards the apex.
From three to twenty days the greatest breadth is usually found
TABLE 4
Average radial breadth of the membrana tectoria and its thickness in radial-vertical
section. Averages of all four turns (charts 2 and 8)
AGE
BODT
WEIGHT
BODY
LENGTH
Outer zone
between free
end of mem-
brane and
labium
Inner zone
labium
vestibulare
and inser-
tion of mem-
brane
Total length
of mem-
brane
Ratios
inner and
outer zone
Thickness
membrane
days
grams
mm.
M
M
M
M
1
5
48
140
37
177
1 3.78
12
3
8
56
134
94
228
. 1.43
32
6
11
63
154
105
259
1.44
32
9
10
58
158
123
281
1.28
27
12
13
60
157
126
283
1.25
25
15
13
75
160
124
284
1.29
28
20
29
95
162
129
291
1.26
38
25
36
104
162
128
290
1.27
34
50
59
125
162
131
293
1.24
35
100
112
159
162
132
294
1.23
36
150
183
190
161
131
292
1.23
32
257
137
175
163
129
292
1.26
38
366
181
191
162
131
293
1.24
35
546
255
213
163
132
295
1.23
34
Ratios 1 546 days
1 1.2
1 3.6
1 1.7
1 2.8
t 12 546 "
1.0
1.0
1.0
1.4
20 5 "
1.0
1.0
1.0
0.9
in turn III, but after this in turn IV. At the bottom of each
column are given the ratios of the radial breadth in each turn
between the several age limits.
These show that after twelve days there is but little change
in the radial breadth of the entire membrane in any turn.
On examining the growth in each zone of the membrane
through the several turns, we find that after three days the outer
zone of the membrane becomes at each age always broader
from base to apex.
31
u
200
150
100
50
o
AGE QAYSH
i i
O
25
50
5O 10O 2OO 3OO 4OO 50O
Chart 2 The radial breadth of membrana tectoria, table 4, figure 1.
Total radial breadth of the membrane.
Radial breadth of outer zone.
*- Radial breadth of inner zone.
40
M
20
n
i
V,
^
9 ~~
* .
c=
/
"^
--
1
^
*
/
G
E
C
A
4~
!
25 50 50 10O 2OO 3OO 4OO 5OO
Chart 3 The thickness of membrana tectoria, table 4.
32
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
ta o
i-
< -S
a
2
S
BS
.
n w
it
T^cOTtiCO-'^
-HOOOOOO
o; (
o;^ ^-^
(N 00
OOOOOOOO
co o !o
rH O
rH O
>> ^
c3
1 O I
rH'HCScouv.S "3:uj
W i i
' co
20-546
GBOWTH OF THE INNER EAR OF ALBINO RAT
33
The values at birth are relatively greater than those at three
days, as noted above, due to the undevelopment of the labium
vestibulare. The inner zone grows in a like manner in breadth,
but not so rapidly as the outer zone, and hence its relative breadth
diminishes gradually from base to apex.
Table 6 shows these relations. While the ratios in the inner
zone decreases from base to apex, those in the outer zone increase.
Thus the ratios in the inner and outer zones according to the
turns go in opposite directions. As stated above, the radial
breadth is generally larger in the outer zone, but this relation
is, in general, reversed in turn I, table 5.
TABLE 6 Condensed
Ratios of the radial breadth of each zone of the membrana tectoria
Ratios according to turns of the cochlea
Ratios between inner and
BOOT
INNER CONE
OUTER ZONE
outer zone
AGE
__ fjfi**T
Turns
Turns
Turns
I-II
I-III
I-IV
I-II
I-II I
I-IV
I
II
in
IV
days
grams
1
5
1:0.8
1:0.5
1:0.0
1:1.2
1:1.3
1:1.4
1:1.8
1:2.8
1:4.3
1:0.0
8
11
:0.9
:0.9
:0.8
:1.4
:1.8
:1.9
:0.8
:1.2
:1.6
:2.0
18
21
:0.9
:0.9
:0.8
:1.4
:1.8
:2.0
:0.8
:1.1
:1.5
:1.9
203
160
:0.9
:0.9
:0.8
:1.4
:1.7
:2.0
:0.8
:1.1
:1.5
:1.8
In turn I the average ratios are, after eight days, smaller than
1.0; therefore, the inner zone is wider than the outer in turn I.
It increases in all ages from turn II toward the apex.
In table 7 are given the ratios between each turn of the cochlea.
The ratios after nine days of age are practically constant according
to age, but those between turns I and II are always smaller
than the others; the ratios for the two latter being alike. The
ratio at one day is, however, an exception, as stated already.
As the measurements show, the membrana tectoria is at birth
relatively undeveloped; it is thin and immature. After birth
it increases rapidly during the first nine days, a statement which
applies generally to the postnatal growth of the organs of the
albino rat. Thus we get a ratio of the radial breadth 1 :1 .7 between
1 and 546 days, but after twelve days the ratios remain prac-
tically 1:1.0. (Table 4.)
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
It is not my purpose to describe the fetal development of
the membrana tectoria, but it is worth while to consider briefly
the zones which compose the membrane; in other words, the parts
of the tympanic wall from which it originated. There are chiefly
TABLE 7
Ratios of the radial breadth of the membrana tectoria according to the turns of the
cochlea
AGE
BODY WEIGHT
Ratios according to turn of the cochlea
I-II
I-II I
I-IV
days
gms.
1
5
1 1.0
1 1.0
1 :0.9
3
8
1.2
1.2
:1.2
6
11
1.2
1.4
:1.3
9
10
1.1
1.3
:1.3
12
13
1.1
1.3
:1.3
15
13
1.1
1.3
:1.3
20
29
1.1
1.3
:1.3
25
36
1.1
1.3
:1.4
50
59
1.1
1.3
: 1.3
100
112
1.1
1.3
:1.4
150
183
1.1
1.3
: 1.3
257
137
1.1
1.3
:1.3
366
181
1.1
1.3
:1.3
546
255
1.1
1.3
:1.3
Chart 4 The total radial breadth of membrana tectoria arranged according
to the turns of the cochlea, table 5.
About middle part of the basal turn (I).
About the beginning of the middle turn (II).
About the middle part of the middle turn (III).
About the beginning of the apical turn (IV). 2
Chart 5 The radial breadth of the inner zone of the membrana tectoria,
according to the turns of the cochlea, table 5.
Chart 6 The radial breadth of the outer zone of the membrana tectoria,
according to the turns of the cochlea, table 5.
* In most cases when the values which have been determined are analyzed
according to the turns of the cochlea, it is found that they increase with later
growth from the basal (I) to the apical (IV) turn and in the order just given in
chart 4. Owing to this uniformity of behavior, some thirteen charts showing
the several values according to turn have been omitted, since the graph given
by the average value is sufficiently informing in each instance.
In the case of those charts which have been retained, and in which the
measurements are according to the turns of the cochlea, the respective turns
I-IV are recorded by characteristic lines similar to those used for them in
chart 4, and in these cases the further designations of the turns are omitted.
350
300
I
ISO
G.E DAYSH
25 5O
50 1OO 2OO 30O 400 500
Chart 4
150
1OO
50
AGE
25 50 50 1OO 200 300 4OO 500
Charts
180
100
DAYS-
25 50 5Q 1OO 2OO 3OO 4OO 5OO
Chart 6
36
two views about this. While a few authors, Kolliker ('67),
Hensen ('63), and recently Hardesty ('08, '15), and others hold
that only the greater epithelial ridge takes part in the formation
of the membrane, most investigators (for example, Bottcher,
'69; Retzius, '84; Rickenbacher, '01; Held, '09; Van der Stricht,
'18) consider that it originates from both the greater and lesser
epithelial ridge. My figure 5, supports the latter view; that is,
while the main part is developed from the greater ridge, the
outer narrow marginal part is secreted from the lesser ridge.
The figure in Quain's Anatomy by Schafer ('09) (vol. 3, part
2, p. 332, llth ed.,) is from the earlier paper of Hardesty and
shows the membrane in the pig as arising from the greater
epithelial ridge only.
Hardesty has corrected this figure in his paper published in
1915. Thus in the very early stage after birth in these forms
we have three zones, an inner, an outer, and a marginal zone.
With age, however, this marginal zone becomes, as Held ('09)
and others agree, gradually smaller and smaller, and finally
it is difficult to differentiate it from the outer zone. Thus for
convenience in measurements I have treated the membrane as
consisting of two zones only.
Comparing the breadth of the inner and outer zones, it is
evident that the outer is always the broader. The ratio is
(table 4) at birth 1 : 3.78, at three days 1 : 1.43, and then gradually
diminishes to 1:1.23 with age.
Now if we examine the ratios of the total breadth of the
membrane according to the turns of the cochlea, we find after
six days that the ratio generally increases from base to apex,
and that these ratios remain nearly constant after nine days
of age, as shown in table 7.
Thus the ratio between turns I and II is 1:1.1; between turns
I and III, 1:1.3; between turns I and IV, 1:1.3. The breadth
of the membrane increases, -therefore, in the albino rat gradually
from the base to the middle part of the middle turn; from this
point it does not increase to the apex.
Since the breadth at the tip of the apex diminishes greatly,
as is generally recognized, Hardesty ('08) found in the pig the
following ratios (table 8):
GROWTH OF THE INNER EAR OF ALBINO RAT
37
Comparing these ratios obtained by Hardesty in the pig with
mine, there appear to be large differences between them. The
reason for these I will discuss later.
When we consider the breadth in each part of the membrane
according to the turn, we find that the increase of the breadth
of the membrane in each turn is due to the development of the
outer zone. The inner zone, which is adherent to the labium
vestibulare, does not increase in the rat as Hardesty ('08/15)
found to be the case for the pig, but on the contrary decreases
from base to apex a relation found by Retzius ('84) in the rabbit,
cat, and man and confirmed by Rickenbacker ('01) in the guinea-
pig. On the contrary, the outer zone increases in breadth from
TABLE 8
Ratios of the breadth of the membrana tectoria according to turn of cochlea (Hardesty)
Kind of animal
Preparation
method
Ratios between
breadth in 7 and
5 half turn
Ratios between
7 and 3 half turn
Ratios between
7 and 1 half turn
Pigs two weeks
of age
Membrane
teased out
Membrane
1 : 1.4
1 :1.7
1 :2.5
teased out
1 :1.8
1 :2.5
1 :2.7
Adult
Membrane in
section
1 : 1.6
1 :2.1
1 :1.8
base to apex, and in each stage the ratios between the successive
turns are nearly the same. These ratios between successive
turns, however, show rather large differences according to the
different authors.
My results (table 5) show that the outer zone in the albino rat
is nearly two times wider at the apex than at the base. This
agrees with what von Ebner ('02) finds in the human cochlea.
When we consider the thickness of the membrane, we find
it thin at birth, but at three days (table 4) it increases rapidly
and reaches almost its greatest thickness. This increase in
thickness arises through the apposition of new layers to the
under surface, as Hasse (73) and others have noted, but very
large differences appear between the figures given by various
authors.
38 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
Kolliker ('67) finds the membrane 45 n thick in the ox. In
the guinea-pig it is 15 ^ in the thickest place, according to
Schwalbe ('87). Middendorp ('67) gets in mammals generally
a very thin membrane, about 1 n thick. Retzius ('84) states
that in the thickest part in the rabbit it measures 27 [x, in the
cat 32 to 50 |x, and in man 24 to 25 [x. Hardesty finds in the
young pig an average thickness of the teased membrane of
50 [x and in an adult hog 119.3 (x. I get 35 (x as an average in
the adult albino rat after twenty days of age, varying from 32
to 38 [x. My result is therefore closest to that for the cat as
obtained by Retzius. These results are plainly influenced b.y
the dissimilar technical methods used by the several investigators.
About the outermost end of the membrane there are still two
different views. One view is that the outer end of the membrane
projects beyond Hensen's prominence; Kolmer ('07; pig, calf
goat and horse); Hardesty ('15; pig, hog) Shambaugh ('10; pig).
Others assert that the membrane terminates with its outer edge
at the outer boundary of the outermost series of the outer hair
cells. My preparations show that in the rat the outer end of
the membrane does not reach Hensen's prominence.
Possibly this difference is due to the technique of preparation.
In the figures drawn by many authors we can recognize many
artifacts and postmortem changes in the cochlea. Even in the
figures of Kolmer ('07) we see these changes, although he injected
the fixing solution through the carotid artery. Held ('09) says
in his criticism of Hardesty 's figures that " figures 6 and 7 wie
schon Hardesty selbst vermutet hat, sicherlich auf einer Ver-
quellung beruhen "
I myself never observed such a gigantic membrane as Hardesty
('08, '15), Shambaugh ('10), and others show in the cochlea
of the pig. On the other hand, I cannot absolutely deny that
there may have been shrinkage in the cochleas prepared by my
methods, though I see no evidence of it.
From our present knowledge, however, the method of vital
fixing is considered the best available, as already maintained by
Siebenmann and Yoshii ('08), Metzner and Yoshii ('09), Nager
and Yoshii ('10), Wittmaack and Laurowitsch ('12), and others.
GROWTH OF THE INNER EAR OF ALBINO RAT 39
By using this vital-fixation method we get perfect sections which
can be used to solve the problem of the shifting of the organ
of Corti an event which I will discuss later.
2. Membrana basilaris. The membrana basilaris of the
cochlea stretches between the limbus laminae spiralis and the
ligamentum spirale. The acoustic terminal apparatus is situated
on it and according to the dominant Helmholtz-Hensen theory,
this membrane is to be considered as very important in tone
perception. The row of the fine holes, foramina nervina,
is generally designated as the inner boundary of this membrane.
Strictly speaking, however, the beginning of the membrane is
at the outer edge of the labium tympanicum, which sharpens at
first beyond the foramina nervina and passes over to the sub-
stance of the membrana basilaris. Practically it is almost
impossible to decide exactly the point of transition. Thus I
have used in the measurement of the membrane the foramina
of the habenula perforata as an inner limiting line following in
this Retzius, ('84) Schwalbe ('87), and others. Here it is to be
mentioned that the organ of Corti lies with its inner portion
not only upon the inner part of the membrane, but extends to
the foramina nervina also.
The membrana basilaris is usually divided into two portions;
the inner, termed the zona arcuata, and the outer, the zona
pectinata. The former stretches from the habenula perforata
across the base of the tunnel of Corti to the outer edge of the
foot of the outer rods of Corti ; the latter extends from this point
to the ligamentum spirale (fig. 2), 5= inner zone, 10= outer zone.
In table 9 (chart 7) are given the values for the total radial
breadth of the membrane, that of each zone, and the ratios
between them. At the bottom of each column are given the
ratios at 1 to 546, 12 to 546, and 20 to 546 days of age. In the
total radial breadth of the membrane, as the table shows, there
are large differences on age from birth to nine days. Between
1 day and three days the increase is 30 |x and between three days
and six days, 28 [A. After nine days the breadth increases more
slowly but continuously to old age.
40
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
In the growth of both zones we see about the same relation.
These increase rapidly from birth till nine (or twelve) days and
after that very slowly. These relations are shown clearly in
the ratios at 1 to 546, 12 to 546, and 20 to 546 days. While after
twelve days the ratios in total breadth and in each zone are
the same, 1:1.1, that for 1 to 546 days is smaller for the outer
zone than it is for the inner zone, thus the inner zone increases
TABLE 9
Radial breadth of Ihe membrana basilaris measured between the foramina nervina
and ligamentum spirale in radial sections on age (chart 7, fig. 2}
AGE
BODY WEIGHT
INNER ZONE
(Zona
arcuata)
OUTER ZONE
(Zona
pectinata)
Total radial
breadth of
the mem-
brane
Ratios between
the radial breadth
of the inner and
outer zone
days
grams
P
M
M
M
1
5
49
75
124
1 1.5
3
8
63
91
154
1.5
6
11
77
105
182
1.4
9 1
10
79
111
190
1.4
12
13
- 88
100
188
1.1
15
13
87
102
189
1.2
20
29
86
106
192
1.2
. 25
36
87
108
195
1.2
50
59
88
107
195
1.2
100
112
92
106
Id8
1.2
150
183
92
107
199
1.2
257
137
92
107
199
1.2
366
181
93
111
204
1.2
546
255
94
113
207
1.2
Ratios 1 546 days
1 1.9
1 1.5
1 1.7
12546 "
1.1
1.1
1.1
20546 "
1.1
1.1
1.1
1 A rat of nine days which could hear, gave the following:
Right side 11
94
103
197
91
104
195
93
104
196
1 : 1.1
considerably after birth, while the outer zone does not grow,
as some authors have imagined, as much as the inner zone.
I will discuss this point later.
Comparing the growths of the radial breadth of the inner
and outer zones, we find that the inner zone is relatively narrow
at nine days; thus the ratios between them are 1:1. 4; after that
period the inner zone increases rapidly, and even at twelve
days the ratio becomes 1:1.1, which is almost the same as in
the adult, 1:1.2.
GROWTH OF THE INNER EAR OF ALBINO RAT
41
In table 10 the radial breadths of the whole membrane and
of its zones are arranged accordingly to the turns of the cochlea
on age. At the bottom of each column are given the ratios
from 1 to 546, 12 to 546, and 20 to 546 days. We see at first
that the total radial breadth at one day is largest in the basal
turn; at three days it becomes larger on passing from the basal
toward the II and III turns, but in turn IV it is again small.
220
M
180
140
100
60
20
i
*
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JH
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1
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r
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E
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fo
25 50 50 , oo 20O 3OO 4OO 5OO
Chart 7 The radial breadth of the membrana basilaris, table 9, figure 2,
distance 11.
Total radial breadth of the membrane.
Radial breadth of the zona pectinata.
Radial breadth of the zona arcuata.
After six days it is a well-known fact that the radial breadth of
the membrana basilaris is narrowest in the basal, and widest
in the apical turn (not the tip of the apex, but the beginning
of the apical turn). These differences are not always the same
between all the turns; those between I and II, and II and III
are marked; those between III and IV are small. The ratios
at 1 to 546 days show those for the upper turn to be largest,
while from 12 to 546, and 20 to 546 days the ratios in all turns
are about 1:1.1.
42
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
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Left side
Average
GROWTH OF THE INNER EAR OF ALBINO RAT
43
In the zona arcuata (inner zone) the same relation is to be
seen in each turn; therefore, in the early period the breadth
is less in turn IV than in the other turns. Very soon, however,
the value in turn IV becomes the largest and diminishes toward
the base. The rate of the growth of this zone, from 1 to 546 days,
is also smallest in turn I, and largest in turns III or IV; the
ratios being in the first 1:1.6, and in the last 1:2.1.
In the zona pectinata (outer zone) we see also similar relations.
TABLE 11
Ratios of the radial breadth of the membrana basilaris according to the turns of the
cochlea on age
AGE
BOOT WEIGHT
Ratios between turns
I-II
I-III
I-IV
days
gms.
1
5
1
1.0
1
1.0
1
1.0
3
8
1.0
1.0
1.0
6
11
1.1
1.2
1.2
9
10
1.1
1.2
1.1
12
13
1.2
1.3
1.3
15
13
1.1
1.3
1.3
20
29
1.1
1.2
1.3
25
36
1.2
1.3
1.3
50
59
1.1
1.3
1.3
100
112
1.1
1.3
1.3
150
183
1.1
1.2
1.3
257
137
1.1
1.2
1.3
366
181
1.1
1.2
1.3
546
255
1.1
1.2
1.3
Only slight differences in the ratios according to age are found.
In table 11 the ratios according to the turns of the cochlea
are given. While from one to three days the ratios are the same
in each turn, 1:1.0, yet after six days those for turns I to II are
smallest, and for I to IV larger, thus showing slight differences
between them.
In the literature we find only one description, that by Retzius
('84) touching the growth of the radial breadth of the membrana
basilaris according to age. He measured this membrane in the
rabbit and cat and got the following values in n (table 12).
44
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
Comparing these values with mine obtained for the albino
rat, it is to be noted that those of Retzius are generally larger
than those for the albino. For example, while I get at birth
only 126 (x in the basal turn, Retzius ('84) obtains 180 [x in the
rabbit and even 270 [x in the cat. As stated above, the radial
breadth increases in the albino rat continuously with age. It
is very peculiar to find in the Retzius table that the breadth
of the membrane in the cat is decidedly larger at birth than at
three and seven days. The average value for the new-born is
315 [x, which is larger than at thirty days, which is 310 [x.
Retzius ' data show the membrane in the rabbit and cat always
wider in the apical than in the basal turn at birth and at two
TABLE 12
Breadth of membrana basilaris according to turns, p. (From Retzius, '84}
RABBIT
CAT
Age
Basal
Middle
Apical
Basal
Middle
Apical
days
New-born
180
270
270
300
375
2
220
272
280
3
.
200
280
7
270
306
211
258
300
10
255
310
390
11
255
300
330
14
300
360
410
30
240
300
390
days. My results, given in table 10, show the reverse at the
ages of one and three days. This is an expression of greater
immaturity in the case of the rat.
In comparisons like the foregoing, several conditions must
be kept constantly in view.
So far as absolute values are concerned, it is to be expected
that these would be unlike in the different mammals, because
the cochleas differ in size. As to the relations between the values
at birth and at maturity, it is plain that these cannot be ex-
pected to agree unless the cochleas of the animals compared
are in the same phase of development at birth. In the foregoing
instances it appears that the cat is relatively precocious, as
compared with the rabbit, while, as might be expected, because
GROWTH OF THE INNER EAR OF ALBINO RAT
45
of their closer zoological relationship, the rat and the rabbit are
in better agreement, although the rabbit appears to be a trifle
more advanced at birth than the rat.
Finally, in the comparison of different series of data, differ-
ences due to the lack of homogeneity in the series of animals
used and to the various techniques employed can hardly fail to
play an important part, and allowance must be made for these
disturbing factors.
When we consider the rate of growth, the ratio of a one to a
fourteen-day-old rabbit is 1:1.6, according to Retzius; therefore,
TABLE 13
Breadth of basilar membrane
ANIMAL
AUTHOR
TURN IN WHICH MEASUREMENT WAS MADE IN M
Basal
Second
Third
Fourth
Average
Man-New-born
Hensen ('63)
235
413
495
381
Man Mature
Retzius ('84)
210
340
360
303
Calf
Kolmer ('07)
200
280
400
293
Pig
Kolmer ('07)
168
200
256
304
232
Goat
Kolmer ('07)
124
384
432
313
Cat
Bottcher ('69)
90
435
263
Cat
Middendorp ('67)
246-275
it has very nearly the value found in the albino. In the cat,
however, the ratio between one and thirty days is 1:0.97; there-
fore, it apparently decreases a bit.
This difference is most readily explained as due to the
precocious development in the cat at birth.
On comparing the radial breadth of the membrane obtained
from several mammals by various authors, we find the following
values (table 13).
The values here given must be read in the light of the various
modifying conditions to which reference has just been made.
46 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
My average value after twenty days is 199 [i; therefore, it
is absolutely the smallest in this series of mammals. The rat
is also the smallest species examined.
As shown in the literature quoted, and also in my own results,
the membrane increases in its breadth in all the mammals ex-
amined from the base toward the apex a relation contrary to
that reported by the older authors (Corti, '51, and others).
This increase is continuous, but is at first more rapid and after-
wards more gradual. The ratios of this increase in the albino
rat are given in table 11.
The next question relates to the breadth of each zone of the
membrane according to age. So far as I know, there is no such
study in the literature, not even in Retzius. In the albino rat,
as shown in table 9, each zone increases in breadth with age.
The rate of growth, however, is somewhat different, and in the
zona arcuata it is greater than in the zona pectinata (1:1.9 and
1 :1.5, respectively), although the absolute value is always greater
in the latter.
As noted above, the membrane increases in its radial breadth
from the basal to the apical turn. How, and in which portion
of the membrane does this increase arise? Henle ('66) first
regarded the breadth of the inner (zona arcuata) as approx-
imately constant.
"Nicht nur in den verschiedenen Regionen einer Schnecke,
sondern, soviel ich sehe, selbst in den Sshnecken verscheidener
Tiere und des Menschen; sie schwankt nur wenig um 0.01 mm."
(Eingeweidelehre des Menschen, 1866, S. 793).
In the second edition of his book ('73) he states, however,
that in the increase of the breadth according to the turn, both
zones seem to take part. Hensen ('63) gets in the zona arcuata
of the base of the human cochlea the breadth of 19 ^ and in the
apex 85 \L. Middendorp ( '68) gives in the cochlea of the cat a
continuous increase of the breadth of the zona arcuata from 94
to 122.5 {A. ."''"'
More detailed data are given in table 14.
According to all these authors, the breadth of both the inner
and outer zones increases from base toward apex and results
GROWTH OF THE INNER EAR OF ALBINO RAT
47
in the increase of the total radial breadth of the membrane
according to turn. My results obtained from the albino rat
agree with these data.
3. Radial distance between the habenula perforata and the
inner corner of the inner pillar cells at base. The measurements
of the radial distance from the habenula perforata to the bases of
the inner and outer pillar cells were taken to determine their
postnatal growth. As already stated, the cells from which the
arch of Corti arises stand at birth nearly vertically and have no
space between them (fig. 4). In the adult, however (fig. 10),
we see a space, the tunnel of Corti lying between them and
changes in the form of the arch occur. To follow these changes
TABLE 14
Breadth of the inner zone of the membrana baeilaria in n
NUMBER Of TURN
First
Second
Third
Fourth
Cat-adult
Bottcher ('69)
60
105
135
Guinea-pig
Winiwarter (70)
45-52
63-68
71-80
80-83
it seems at first necessary to study the growth of the pillar
cells and of the other elements in the organ of Corti. At the
same time we must take into consideration the inward shifting of
the organ of Corti, first studied by Hensen. This shift inward
of the organ is, according to Hensen, chiefly caused by the
wandering of the pillar cells, especially the inner pillar cell.
Therefore, it seemed necessary to determine the radial distance
of the pillar cells from the habenula perforata at different ages
before discussing this interesting problem.
In table 15 are given the values for the radial distances between
the habenula perforata and the inner corner of the inner pillar
cell at its base according to age (figs. 4 to 9). As we see, the
average value increases till three days of age, then vanishes
suddenly, though at six days we have a measurable interval
in the upper turns of the cochlea. Comparing these distances
according to the turn, they are smallest in turn I and increase
48
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
toward the apex. In some cases, at six days, we have no interval
in the basal turn, but in the higher turns an interval gradually
appears and at the apical turn is largest. This table shows,
therefore, that the inner corner of the base of the inner pillar
cell lies at birth outward from the habenula perforata at an
TABLE 15 Condensed
Radial distance between the habenula perforata and the inner corner of the inner
pillar at base on age
AGE
BODY
WEIGHT
TURNS OF THE COCHLEA M
I
II
ill
IV
Aver.
days
1
5
19
22
22
23
22
3
8
23
28
28
30
27
6
11
In one case 5
In 2 cases 10
14
18
In other 3 cases
In other cases
9
10
12
13
average distance of 22 \L. At three days of age the inner corner
moves farther outward with the developing membrana basilaris
and the distance increases from the base to the apex. Between
three to six days this outward movement not only stops, but
reverses its direction, and at six days it often becomes zero in
the basal turn. Bottcher ('72) finds in the cat the following
values for this interval in \i (table 16).
TABLE 16
CAT EMBRYO 11 CM. LONG
ADULT CAT
I
II
ill
IV
Average
I
II
ill
IV
Average
15
39
30
30
29
3
3
3
3
3
TABLE 17
BABBIT
CAT
AGE
Basal
turn
Middle
Apical
Average
Basal
Middle
Apical
Average
days
New-born
300
300
300
300
5
40
45
30
2
10
12
30
17
3
3
36
7
11
18
GROWTH OF THE INNER EAR OF ALBINO RAT 49
Retzius ('84) studied this distance in the rabbit and cat and
gets the values given in Table 17.
Comparing the values of these two authors with my own,
there are of course some differences. While in the rabbit the
interval is large at one day, it is greatly diminished at two days
of age. At three days the inner corner of the cell reaches the
habenula perforata. In the cat the values are nearer to mine.
The fact that the values increase from base toward apex is to
be seen here also. This peculiar phenomenon appears, therefore
not only in the albino rat, but also in the rabbit and the cat
during the earliest stage of postnatal life.
4- The radial distance between the habenula perforata and the
outer corner of the inner pillar cell (resp. the inner corner of the
outer pillar cell) at base. This measurement is difficult. As we
know, the inner and outer pillar cells in the albino are from birth
till nine days of age in contact with each other along their whole
length, and therefore they do not yet surround the space forming
the tunnel of Corti. At about nine days, however, the tunnel
appears while the cells remain in contact by their bases. It
is almost impossible to determine the line of contact on the
basilar membrane in my preparations. To get the radial distance
between the habenula perforata and the outer corner of the inner
pillar cell I have proceeded therefore as follows:
First, I have measured this distance directly up to nine days
of age; after that this distance consists of the sum of the radial
basal breadth of the inner pillar (not pillar cell) and the breadth
of the inner basal cell on the basilar membrane. Since it is
impossible to get the latter value directly in my sections, I
considered that half of the radial distance between the outer
corner of the inner pillar and the inner corner of the outer pillar
would be equivalent to it.
Of course, I do not know whether the value of the sum of
these two distances is at all ages, identical with the distance
between the habenula perforata and the outer corner of the inner
pillar cell at its base. I believe, however, that a systematic
study of the growth of this distance will be significant.
50
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
In table 18 are given the values for the radial distance between
the habenula perforata and the outer corner of the inner pillar
at base up to nine days of age. As shown, these values, on the
average, increase with age. The increase of this distance means
that the base of the inner pillar cell spreads outward more and
more.
When we consider this distance according to the coil of the
cochlea, it is at birth about the same through all the turns
(table 18; at three days it increases up to turn III, and in turn
TABLE 18
Radial distance between the habenula perforata and the outer corner of the inner
pillar at base on age
TURNS OF COCHLEA M
AGE
BODY WEIGHT
I
II
III
VI
Average
days
grams
1
5
40
41
39
39
40
3
8
48
49
50
48
48
6
11
38
45
58
53
49
9
10
44
46
56
53
50
IV the value is the same at the apex as at the base. At six days
the value in turn III is also largest, and next largest in turn IV.
At nine days of age the same relations are to be seen.
In table 19 (chart 8) are given the values for the radial basal
breadth of the inner pillar (not pillar cell) on age. At the bottom
of the last column are the ratios from 6 to 546, and 20 to 546
days. As above noted, the rod can be followed at birth from
the upper part to near the base of the cell (fig. 4). At three days
(fig. 5), its base reaches the basilar membrane as a thin and slender
thread, but we cannot measure its basal breadth accurately.
During the next few days it increases in radial breadth rapidly,
and at six days has the average value of 29 [/. (table 19). After
nine days it decreases distinctly till twenty days, after which
the value remains nearly constant. These relations are evident
in the ratios. While the breadth at six days is about twice
that at 546 days, that at twenty days has the same value.
GROWTH OF THE INNER EAR OF ALBINO RAT
51
According to the turn of the cochlea, the values from nine
to fifteen days become gradually larger on passing from the
base toward the apex. After twenty days, however, this relation
vanishes, and the values become nearly the same through all
TABLE 19
Radial basal breadth of the inner pillar on age (chart 8)
day*
1
3
ti
9
12
15
20
25
50
100
150
257
366
546
Ratios 6
20
WEIOHT
BODY
TURNS OF THE COCHLEA M
I
II
III
IV
Average
grams
5
8
11
29
31
27
27
29
10
28
28
33
35
31
13
18
19
22
25
21
13
18
18
19
19
19
29
14
15
15
15
15
36
14
15
14
15
15
59
14
14
14
13
14
112
14
14
14
13
14
183
15
15
15
15
15
137
15
15
15
15
15
181
16
17
15
15
16
255
15
14
16
15
15
-546 days
1 :0.5
-546 "
: l.o
40
U
20
n
"
\
Ab
DA'
/q
a
25 5O 5Q IOO 20O 3OO 4OO 5OO
ChartS. The radial basal breadth of the inner pillar (not pillar cell),
table 19, figure '2, distance 3.
the turns. In table 20 the ratios of the turns I to II, I to III,
and I to IV are given for three age groups (condensed from table
52
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
From the data given by Retzius ('84) we get the values in jx
of the radial basal breadth of the inner pillar in the rabbit and
cat as follows (table 21).
Comparing these values with my own, it is to be noted that
Retzius' measurements in the rabbit agree perfectly at the
earliest stage with those in the albino rat. Also we find in the
TABLE 20 Condensed
Ratios of the radial basal breadth of the inner pillar according to the turns of the
cochlea on age
RATIOS
BETWEEN TTTBN8
AGE
BODY WEIGHT
I-II
I-III
I-IV
days
grams
8
11
1 1.0
1 1.0
1 1.1
14
13
1.1
1.2
1.3
189
124
1.0
1.0
1.0
TABLE 21
Radial basal breadth of inner pillar in n (Retzius)
BABBIT
CAT
Age
Basal
turn
Middle
Apical
Average
Basal
Middle
Apical
Average
days
New-born
11
2
3
12
7
15
12
15
14
10
15
10
17
18
18
18
11
15
15
14
15
15
12
14
30
9
12
15
12
rabbit at seven days values homologous with those obtained in
the albino rat at fifteen days of age, only in the rat the breadth
is absolutely greater. In the cat the values at seven days of
age are about the same, or a bit smaller, than those in the albino
rat. Here again the rabbit is a trifle more precocious than the
rat, and the cat much more so.
Table 22 (chart 9) shows the values for the radial distance
between the outer corner of the inner pillar (not pillar cell)
GROWTH OF THE INNER EAR OF ALBINO RAT
53
TABLE 22
Radial distance between the outer corner of the inner pillar and the inner corner of
the outer pillar at base on age (chart 9)
AGE
BODY WEIGHT
TURNS OF THE COCHLEA M
I
II
III
IV
Average
days
grams
1
5
3
8
6
11
25
28
29
34
29
9
10
27
30
35
30
31
12
13
37
41
51
53
46
15
13
35
46
56
56
48
20
29
43
53
66
68
58
25
36
42
58
67
68
59
50
59
41
54
68
74
59
100
112
44
59
71
78
63
150
183
43
59
68
76
62
257
137
46
56
66
75
61
366
181
45
57
68
74
61
546
255
47
60
71
74
63
Ratios 6546 days
12546 "
20546 "
2.2
1.4
1.1
ou
14,
60
40
20
r\
<
t=
-
MM
.
=
-
1
/
i
/
i
1
G
E
DA>
/C
1
13
o
25
50
50 1OO 20O 3OO 40O 5OO
Chart 9. The radial distance between the outer corner of the inner pillar
(not pillar cell) and the inner corner of the outer pillar (not pillar cell) at base,
table 22, figure 2, distance 6.
54
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
and the inner corner of the pillar (not pillar cell) at the base,
on age. At the bottom of the last column are given the ratios
from 6 to 546, 12 to 546, and 20 to 546 days. As just stated,
the inner, and especially the outer rods, do not appear in the
respective pillar cells at the earliest stage, the latter becoming
evident a bit later than the former. After six days of age the
distance between them can be determined.
As table 22 shows, this distance increases at first rapidly,
then more slowly with age. This agrees with the growth of the
membrana basilaris, as already noted. While the value at 546
days is over twice as large as at six days, it is but little larger
than at twenty days, as the ratios show. Moreover, the distance
increases from the base toward the apex rapidly up to turn
TABLE 23 Condensed
Ratios of the radial distance between the outer corner of the inner pillar and the
inner corner of the outer pillar, at base according to turns
of the cochlea on age
BATIO8 BETWEEN TURNS
I-II
i-m
I-IV
days
grams
8
11
1 : 1.1
1 : 1.2
1 : 1.2
14
13
: 1.2
: 1.5
: 1.5
189
124
:1.3
:1.5
:1.7
III and less rapidly to turn IV. This relation is more concisely
presented in table 23. Retzius ('84) gives the value of this
distance in the rabbit and the cat as follows (table 24).
The table 24 shows that there is no measurable distance
between the outer corner of the inner pillar and the inner corner
of the outer pillar at the very early stage in the rabbit, and this
result is like that for the albino rat. Later the distance is larger
in the rabbit than in the rat. The rate of increase of the values
from the base to the apex is, however, similar in both forms.
In the cat, on the other hand, there is already at birth a large
distance between the pillars. The cochlea of the cat is there-
fore at this period more advanced in this character than that of
the rabbit or rat, but in the cat also the distance tends to in-
crease from the base toward the apex.
GROWTH OF THE INNER EAR OF ALBINO RAT
55
In table 25 (chart 10) are given the values for the radial
distance between the habenula perforata and the outer corner
of the inner pillar cell (resp. the inner corner of the outer pillar
cell) at the base according to age. This table is derived from
tables 18, 19, and 22. The values from one to nine days of age
are from table 18. Those after twelve days consist of the sum
of the values in table 19 plus the one-half of those given in table
22 (fig. 2 value for bracket 3 plus one-half the value for bracket
6).
TABLE 24
Radial distance between the outer corner of the inner pillar and inner corner of the
outer pillar in n (Retzius)
RABBIT
CAT
Age
Basal
turn
Middle
turn
Apical
turn
Average
turn
Basal
turn
Middle
turn
Apical
turn
Average
turn
days
New-born
64
2
3
45
7
57
75
75
69
50
75
10
52
72
74
66
11
75
95
14
63
100
99
87
30
66
93
90
83
The values increase gradually after birth till nine days, when
they reach a maximum, and then decrease, but increase again
very gradually till old age. If this method of measurement is
accepted, then the inner corner of the inner pillar cell lengthens
inward at the base in the earlier stages. At the time when the
inner pillar reaches the habenula perforata, the outer corner
of the inner pillar has not yet moved inward, and thus the breadth
of the base is largest. After the inward wandering of the inner
pillar cell, the base diminishes a little in its breadth; then it
increases slightly with advancing age.
When considered according to the turn of the cochlea, this
measurement generally increases from the base to the apex,
but more rapidly from turn I to turn III, and only slightly from
56
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
TABLE 25
Radial distance between the habenula perforata and the outer corner of the inner
pillar cell (resp. the inner corner of the outer pillar cell) at base on
age. Derived from tables 18, 19 and 22 (chart 10)
AGE
BODY WEIGHT
TURNS OF THE COCHLEA M
I
II
III
IV
Average
days
grams
1
5
40
41
39
39
40
3
8
46
49
49
49
48
6
11
38
45
58
53
49
9
10
44
46
56
53
50
12
13
36
45
50
50
45
15
13
36
41
47
47
43
20
29
36
42
48
49
44
25 .
36
35
44
48
49
44
50
59
35
41
48
50
44
100
112
36
44
50
52
46
150
183
36
45
49
53
46
257
137
38
43
48
51
45
366
181
39
45
49
52
46
546
255
39
44
52
52
47
Ratios 1 546 days
9546 "
12546 "
20546 "
1.2
0.9
1.0
1.1
60
JLL
40
20
c\
^
r*
r^
_ !
1
e=
-_
G
^
c
A
/s-
25
50
50 1OO 2OO 3OO 4OO 5OO
Chart 10 The radial distance between the habenula perforata and the
outer corner of the inner pillar cell (resp. the inner corner of the outer pillar
cell) at base, table 25, figure 2, distance 8.
GROWTH OF THE INNER EAR OF ALBINO RAT
57
turn III to IV. Table 26 shows this relation. While at birth
the ratio is in all turns the same, 1 :1.0, at other ages it is always
higher. Retzius ( '84) gives the results obtained from the rabbit
and the cat as follows (table 27).
TABLE 26 Condensed
Ratios of the radial basal distance between the habenula perfcrata and the outer
corner of the inner pillar cell (resp. the inner corner of the outer pillar
cell) at base on age according to the turns of the cochlea
RATIOS BETWEEN TURNS
AGE
BODY WEIGHT
I-I1
I-HI
I-IV
days
gram*
1
5
1 1.0
1 :1.0
1 :1.0
8
11
1.2
:1.4
: 1.3
18
21
1.2
:1.3
: 1.3
213
138
1.2
:1.S
:1.4
TABLE 27
Distance between the habenula perforata and the outer corner of the inner pillar
cell in n (Retzius)
Age
Basal
turn
Middle
turn
Apical
turn
Average
turn
Basal
turn
Middle
turn
Apical
turn
Average
turn
days
New-born
30
45
39
38
60
60
60
60
2
30
36
30
32
3
44
60
7
37
46
45
43
45
69(?)
65
60
10
39
52
48
46
11
60
66
75
67
14
40
54
51
48
30
60
60
At the earlier stage this distance in the rabbit is a little less
than in the rat. Soon after, however, it becomes about the same.
In the cat the values are generally larger than in the rat.
5. Radial basal breadth of the outer pittar cett (including
the outer pillar). The measurement of the radial basal breadth
of the outer pillar cell is difficult. At the earlier stage, in which the
inner and outer pillar cells are in contact with each other along
58
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
Radial basal breadth of the outer pillar cell (including the outer pillar) from one
to nine days of age
TURNS OF THE COCHLEA M
AGE
BODY WEIGHT
I
II
III
IV
Average
days
grams
1
5
10
9
8
8
9
3
8
15
16
15
12
15
6
11
26
28
28
33
28
9
10
26
30
30
35
30
TABLE 29
Radial basal breadth of the outer pillar on age (chart 11)
AGE
BOOT WEIGHT
TURNS OF THE COCHLEA M
I
II
III
IV
Average
days
grams
1
5
3
S
6
11
10
14
16
17
14
9
10
15
18
18
21
18
12 .
13
14
23
25
22
21
15
13
17
21
23
20
20
20
29
13
13
16
15
14
25
36
14
13
14
14
14
50
59
14
14
15
14
14
100
112
14
15
16
15
15
150
183
15
15
15
16
15
257
137
15
16
17
17
16
366
181
15
16
17
18
16
546
255
16
15
17
17
16
Ratios
1
2
40
A
20
n
6546 days 1
2546 "
0546 "
1.1
0.8
1.1
t
\,
1
-=a
<
-<
,
G
D
A'
^
i
25
50
5O 1OO 2OO 300 4OO 500
Chart 11 The radial basal breadth of the outer pillar (not pillar cell)
table 29, figure 2, distance 7.
GROWTH OF THE INNER EAR OF ALBINO RAT
59
their whole length, we can easily measure this distance. After
twelve days, however, the breadth consists of the sum of the
radial breadth of the outer pillar and the half of the radial
distance between the outer corner of the inner pillar and the
inner corner of the outer pillar, as previously explained.
In table 28 are given the values for the radial basal breadth
of the outer pillar cell (including the outer pillar) from birth
to nine days of age. These values show a rapid increase. Ac-
cording to the turn of the cochlea, the breadth at birth diminishes
from the base to the apex. At three days it increases already in
turn II, but at the later ages it increases gradually from the
base to the apex.
TABLE 30 Condensed
Ratios of the radial basal breadth of the outer pillars on age according to the
turns of the cochlea
RATIOS BETWEEN TURNS
AGE
BODY WEIGHT
I-II
I-III
I-IV
days
grams
8
11
1 -1.2
1 1.3
1 1.5
14
13
:1.4
1.5
1.3
189
124
: 1.0
1.1
1.1
In table 29 (chart 11) are given the values for the radial
basal breadth of the outer pillar (not pillar cell). As in the case
of the inner pillar, here also the outer pillar first appears distinctly
at six days of age. After the continuous increase of the values till
twelve to fifteen days, they decrease suddenly at twenty days,
and then increase again very slowly. This relation is clearly
shown by the ratios at the bottom of the last column. That
the values tend to increase from the base toward the apex is
also shown, though there are some exceptions. Table 30 gives
the condensed results.
From Retzius' work ('84) we have calculated the values for
the radial basal breadth of the outer pillar in the rabbit and cat
as follows (table 31).
There are large differences between my results and those
of Retzius during the earlier stage, especially in the rabbit.
60
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
At birth, the inner pillar has not yet distinctly developed at
the base of the pillar cell in the rabbit and the rat, as above
stated. We know that the development of the elements of
the cochlea proceeds generally from the axis to the periphery, as
TABLE 31
Radial basal breadth of outer pillar measured in n (from Retzius)
RABBIT
CAT
Age
Basal
turn
Middle
turn
Apical
turn
Average
Basal
turn
Middle
turn
Apical
turn
Average
days
,
New-born
15?
12?
7?
11?
25
15
2
50
45
44
46
3
20
7
28
28
17
24
18
20
18
19
10
31
30
37
33
11
30
19
14
28
25
18
24
30
10
15
15
13
TABLE 32
Radial basal breadth of the outer pillar cells on age, based on tables 22, 28, and
29 (charts 12 and 18)
AGE
BODY WEIGHT
TURNS OP THE COCHLEA M
I
II
III
IV
Average
days
grams
1
5
10
9
8
8
9
3
8
15
16
15
12
15
6
11
26
28
28
33
28
9
10
26
30
30
35
30
12
13
33
38
48
52
43
15
13
35
44
50
48
44
20
29
35
40
49
49
43
25
36
35
42
48
48
43
50
59
35
41
49
51
44
100
112
36
45
52
54
47
150
183
36
45
49
54
46
257
137
38
44
50
53
46
366
181
38
43
51
55
47
546
255
40
45
53
54
48
Ratios 1 546 days
9546 "
12546 "
20546 "
1 :5.4
: 1.6
: 1.1
: 1.1
GROWTH OF THE INNER EAR OF ALBINO RAT
61
Held ('09) and others have pointed out. Yet, according to
Retzius, the outer pillar develops in the rabbit earlier than does
the inner pillar. This result seems to me very peculiar, but,
at present, I am unable to explain it.
In table 32 (charts 12 and 13) are given the values for the
radial basal breadth of the outer pillar cells. These data are
ou
M.
40
20
.-'
-
>-i
^
-
a*
-^
'
1
/
r~
G
:
DA >
/c
25 50 50 1OO 20O 30Q 4(X) 5QO
Chart 12 The radial basal breadth of the outer pillar cell, table 32, figure 2,
distance 9.
5O 50 1OO 2OO 30O 40O 50O
Chart 13 The radial basal breadth of the outer pillar cell, according to
the turns of the cochlea, table 32, figure 2, distance 9.
derived from tables 22, 28, and 29. At the foot of the last column
are given the ratios from 1 to 546, 9 to 546, 12 to 546, and 20
to 546 days. The values increase rapidly during the earlier
stage, but after twelve days very slowly, as the ratios show.
The breadth is, at birth, largest in the basal and smallest
in the apical turn. Very soon, however (six days), the reverse
62
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
relation appears, and the breadth increases from the base
to turn III relatively rapidly, but from turn III to IV slowly.
In table 33 the ratios are given in a condensed form. The radial
breadth of the outer pillar cells as given by Retzius ('84) are
as follows (table 34.)
TABLE 33 Condensed
Ratios of the radial basal breadth of the outer pillar cells on age according to
turns of cochlea
RATIOS BETWEEN TtTRNS
AGB
BODY WEIGHT
I-II
i-in
I-IV
days
grams
1
5
1 :0.9
1 0.8
1 :0.8
8
11
1 1.1
1.2
:1.3
18
21
:1.2
1.4
: 1.4
213
138
:1.2
1.4
: 1.4
TABLE 34
Radial basal breadth of the outer pillar cells in n (Retzius)
RABBIT
CAT
AOE
Basal
turn
Middle
turn
Apical
turn
Average
turn
Basal
turn
Middle
turn
Apical
turn
Average
turn
days
New-born
21
22
23
22
36
30
30
32
3
30
40
30
33
3
36
30
7
65
66
60
64
36
54
36
42
10
52
60
69
60
'
11
50
60
18
43
14
57
80
80
72
30
60
60
This table shows that the breadth of the outer pillar cell in-
creases in the rabbit and the cat continuously from birth to
old age, as I have found in the rat. Also the value is generally
smallest in the base, largest in the apex, though there are some
exceptions. The main differences between the results of Retzius
and mine is that the values in the rabbit are larger than in the
rat. This is probably due to the differences in the size of the
animals.
GROWTH OF THE INNER EAR OF ALBINO RAT 63
6. The radial distance between the habenula perforata and
the outer border of the foot of the outer pillar cell. The deter-
mination of this distance is deemed necessary not only as a datum
on growth in general, but also for its bearing on the difficult
question of the shifting of the outer pillar cell, to be discussed
later. On the other hand, this distance is identical with the
radial length of the zona arcuata of the membrana basilaris
(table 7. inner zone).
In table 35 (chart 14) are given the values for the radial
distance between the habenula perforata and the outer corner
of the outer pillar cell at base. At the foot of each column are
given the ratios at 1 to 12, 1 to 20, 1 to 546, and 20 to 546 days.
As table 35 shows, the distance increases continuously from birth
to old age, rapidly up to twelve days, but later gradually. Up
to three days the distance is slightly larger in the lower turns, but
after this age the relation is reversed, and this persists through life.
The increasing ratio of the distance for each turn according
to age is smallest in turn I and largest in turn IV. The ratios
for the condensed data are given in table 36. While the ratio
at birth is the same in each turn, 1:1.0, that of turn I to II is
smallest for every condensed age. Also it is to be seen that the
increase of the ratio in turn I to II is smallest and that in turns
I to IV is largest. In Retzius' work ('84) we find the following
values for this distance (table 37).
Table 37 shows that in the rabbit the growth changes are
similar to those in the rat, though the absolute values are somewhat
larger. As hi preceding determinations, the values for the cat
do not stand in the same relation as those for the rabbit, but
indicate precocity. Some corresponding observations by Hensen,
Bottcher, and others will be presented later.
7. The greatest height of the greater epithelial ridge (der grosse
Epithelwulst (Bottcher) s. Organon Kollikeri) resp. of the inner
supporting cells (fig. 4, G). The so-called greater epithelial ridge
is a prominence formed by high cylindrical pseudostratified cells.
It is situated axialward on the tympanic wall and continued
outward to the lesser epithelial ridge. About the fate of this
ridge there were various divergent opinions among the older
64
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
authors. Now, the view of Bottcher ( '69) is generally accepted.
This large prominence vanishes during development, and instead
of it a deep and wide furrow lined with low epithelium appears.
These epithelial cells become peripherally higher and finally lean
TABLE 35
Radial distance between habenula perforata and the outer corner of the outer pillar
cells at base on age (chart 14)- For the average values
see the third column in table 9
AGE
BODY WEIGHT
TURNS OF TBE COCHLEA M
I
II
III
IV
Average
days
yrams
1
5
50
50
48
48
49
3
8
63
65
64
58
63
6
11
64
73
86
86
77
9
10
70
76
86
86
80
12
13
69
83
98
100
88
15
13
70
84
98
95
87
20
29
71
81
96
98
87
25
36
71
86
95
97
87
50
59
69
83
96
102
88
100
112
73
88
101
106
92
150
183
73
89
98
107
92
257
137
76
87
98
107
92
366
181
76
89
100
107
93
546
255
78
89
104
106
94
Ratios 1 12 days
1 20 "
1546 "
20546 "
1.4
1.4
1.6
1.1
: 1.7
: 1.6
:1.8
: 1.1
1 -2.0
:2.0
:2.2
1 :2.1
:2.0
:2.2
: 1.1
: 1.8
: 1.8
: 1.9
: 1.1
100
80
60
40
AG^E DAYSH
O
25 5O 50 too 2OO 3OO 40O 500
Chart 14 The radial distance between the habenula perforata and the
outer corner of the outer pillar cell at base, table 35, figure 2, distance 5.
GROWTH OF THE INNER EAR OF ALBINO RAT
65
on the inner supporting cells, which are termed ' Grenzzellen '
by Held ('02). The latter belong, of course, to this ridge, since
the inner hair cell marks the outmost row in the ridge. The
'Grenzzellen' of Held, however, are different from other high
cylindrical cells in the ridge, as they have a very intimate relation
with the ' Phalangenzellen ' of Held, stand with their bases just
TABLE 36 Condensed
Ratios of the radial distance between the habentda perforata and the outer corner
of the outer pillar cells at base on age
RATIOS BETWEEN TURNS
AVERAGE AGE
AVERAGE BODY
WEIGHT
I-II
i-in
I-IV
days
grams
1
5
1 :1.0
1 :1.0
1 :1.0
8
11
: 1.1
:1.3
: 1.2
18
21
:1.2
: 1.4
: 1.4
213
138
: 1.2
: 1.3
: 1.4
TABLE 37
Radial distance between habenula perforata and the outer corner of the outer pillar
cells at base in n (Retzius)
RABBIT
CAT
Age
Basal
Middle
Apical
Average
Basal
Middle
Apical
Average
turn
turn
turn
turn
turn
turn
turn
turn
days
New-born
75
80
75
77
105
105
120
110
2
80
90
100
90
3
80
120
7
100
115
107
107
78
110
120
103
10
100
120
129
116
11
120
129
108
119
14
106
140
129
125
30
85
120
120
108
outward from the habenula perforata and serve to support the
inner hair cell as Deiters' cells support the outer hair cells.
Thus the greater ridge includes in its prominence three kinds
of cells, the high cylindrical cells, the 'Grenzzellen' of Held and
the inner hair cell.
The greatest height of this ridge is not situated at a fixed
point, but first lies somewhat outward from the middle part and
66
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
after the furrow appears, passes outward towards the inner
supporting cells. Thus the greater ridge decreases in thickness
from birth to nine days of age, then increases gradually to twenty
days. After twenty-five days the values diminish again very
slowly but continuously.
In table 38 (charts 15 and 16) are given the values of the greatest
height of the greater epithelial ridge from the basilar membrane
TABLE 38
Greatest height of the greater epithelial ridge (resp. of the inner supporting cells)
on age (charts 15 and 16)
Bodv wcifitlitj
TURNS OF COCHLEA M
I
II
III
IV
Average
height
days
1
grams
5
68
65
66
63
66
3
8
49
49
56
57
53
6
11
40
40
41
40
40
9
10
36
40
41
42
40
12
13
38
41
48
53
45
15
13
44
46
52
58
50
20
29
50
53
63
66
58
25
36
51
51
63
63
57
50
59
50
50
59
63
56
100
112
48
49
59
63
55
150
183
47
49
56
61
53
257
137
47
51
56
62
54
366
181
46
49
57
60
54
546
255
44
50
56
60
53
Ratios 1 9 days 1:0.6
12 20 " :1.3
12546 " :1.2
20546 " :0.9
1546 " :0.8
through the summit of the supporting cells, according to age.
At the bottom of the last column is given the ratio at 1 to 9,
1 to 546, 12 to 20, 12 to 546, and 20 to 546 days of age.
The values in turn I are at birth the largest, but at three
days the relation is reversed and remains so in the later age
groups. Table 39 shows this relation from the condensed data.
Retzius ('84) gives in the rabbit and cat the following values
(table 40).
GROWTH OF THE INNER EAR OF ALBINO RAT
67
In the rabbit the values decrease from birth till ten days,
then increase; therefore, they agree in general with my results
50
40
30
;
25
50 50 10O 20O 30O 40O 500
Chart 15 The greatest height of the greater epithelial ridge (resp. of the
inner supporting cells) table 38, figures 4 to 12.
70
44
60
5O
40
30
s
o
25
50
50 IOO 20O 3OO 4OO 500
Chart 16 The greatest height of the greater epithelial ridge (resp. of the
inner supporting cells) arranged according to the turns of the cochlea, table 38,
figures 4 to 12.
on the rat, while in the cat they diminish from birth till thirty
days though irregularly.
The absolute values are greater for the rabbit than for the
rat during the earlier stage, but afterwards they are similar.
68
In the cat the early data give values similar to those for the rat,
but the later values are lower.
Bottcher's observations ('69) on the cat, calf, and sheep also
give larger values than mine. In the cat the greater ridge has
an average height of 75 [x and in both the others of 90 \L. Therefore,
even in the same animal (cat) there are large differences in the
data presented by different authors.
TABLE 39 Condensed
Ratois of the greatest height of the greater epithelial ridge (resp. of the inner sup-
porting cells) according to the turns of the cochlea on age
Average age
Average body
weight
RATIOS BETWEEB TURNS
I-II
i-in
I-IV
days
grams
1
5
1 :1.0
1 1.0
1 :0.9
8
11
: 1.0
1.1
: 1.2
18
21
:1.1
1.2
:1.3
213
138
:1.0
1.2
:1.3
TABLE 40
Greatest height of the greater epithelial ridge measured through the inner supporting
cells, in p. (Retzius)
RABBIT
CAT
Age
days
Basal
turn
Middle
turn
Apical
turn
Average
turn
Basal
turn
Middle
turn
Apical
turn
Average
turn
New-born
78
99
90
89
45
75
6S
63
2
60
90
90
80
3
40
84
7
51
68
63
61
40
54
63
52
10
36
54
56
49
11
50
58
66
58
14
51
51
51
51
30
30
.
45
45
40
Gottstein ('72) thinks that the greater epithelial ridge does
not diminish its height for some time after birth, but through
the outward development of the labium tympanicum, and in
addition to this through the growth of the labium vestibulare,
the sulcus spiralis internus arises. He does not give measurements.
GROWTH OF THE INNER EAR OF ALBINO RAT 69
His idea was strongly opposed by Bottcher ( 72) and my results
are also opposed to Gottstein's view.
8. The radial distance between the labium vestibulare and the
habenula perforata. The purpose of this measurement is to
determine how the habenula perforata stands in relation to its
surroundings during the development of the cochlea. The meas-
urements of this distance is difficult. During the earlier stages,
the labium vestibulare is quite undeveloped, especially in the
upper turns. At birth we see on the inner surface of the greater
epithelial ridge a small prominence under which the epithelial
cells are short and pressed together so that the nuclei seem to be
arranged in several rows (fig. 4). This appearance is due to the
invasion of the subjacent connective tissue into the epithelium.
Thus the vestibular lip arises. We do not see a furrow at this
time and cannot use the top of the furrow as a point for measuring
as did Hensen ('63) in the ox and Bottcher ('69); in the em-
bryo cat). To the measure the distance between the insertion of
Reissner's membrane and the habenula perforata has no meaning
for my purpose, because the length of the limbus laminae spiralis
changes with age.
Thus I have measured the distance between the small epithelial
prominence on the axial side of the greater ridge, corresponding
to the edge of the labium vestibulare, and the habenula perforata.
In table 41 (charts 17 and 18) are given the -values of the radial
distance between the labium vestibulare and the habenula
perforata. At the foot of the last column are given the ratios
from 1 to 546, 9 to 546, and 20 to 546 days. As we see, the
values are a little bit smaller at the earlier stage. After nine
days they are almost the same in every stage. The small differ-
ences at the earlier and later stages are probably due to the
retarded development of the labium vestibulare.
When we consider the values for this distance in each turn,
it is evident that these increase from base to apex. In the con-
densed table 42 this relation is shown.
Hensen ('63) finds that the distance from the top of the furrow
to the habenula perforata is in the fetal calf and in the ox the
70
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
same, 255 [x. He considers the holes of the habenula as a ' punctum
fixum. ' Bottcher ('69, 72) agrees with Hensen and gets in the
cat embryo and the adult cat the following values (table 43).
TABLE 41
Radial distance between the labium veslibulare and the habenula perforata on age
(charts 17 and 18)
AGE
BODY WEIGHT
TURNS OP THE COCHLEA M
I
II
III
IV
Average
days
grams
1
5
100
108
120
130
115
3
8
80
110
130
137
114
6
11
82
105
135
137
115
9
10
83
108
137
145
118
12
13
80
102
139
148
117
15
13
82
107
144
157
122
20
29
84
106
146
153
122
25
36
82
105
147
150
121
50
59
82
104
137
147
118
100
112
80
103
151
154
122
150
183
80
107
141
144
118
257
137
83
105
143
150
120
366
181
79
105
135
149
117
546
255
79
105
143
150
119
Ratios 1 546 days
9546 "
20546 "
1.0
1.0
1.0
TABLE 42 Condensed
Ratios of the radial distance between the labium vestibulare and the habenula
perforata according to turns of the cochlea
RATIOS BETWEEN TURNS
AVEKAGE AGE
WEIGHT
I-II
I-II I
I-IV
days
grams
1
5
1 1.1
1 1.2
1 1.3
5
10
1.3
1.6
1.8
141
93
1.3
1.7
1.8
Comparing the results of both Hensen and Bottcher with
my own, the values obtained by Hensen are large, as would
be expected in the larger animal. The cat and rat however,
give similar values. We conclude, therefore, that broadly speak-
GROWTH OF THE INNER EAR OF ALBINO RAT
71
ing, the habenula perforata is to be considered as a 'punctum fix-
urn, 'at least after birth.
9. The radial distance be'.ween the labium vestibulare and the
inner edge of the head of the inner pillar cell To measure the
140
120
1OO
AGE DAYS-
25
50
50 1OO 2OO 3OO 40O 500
Chart 17 The radial distance between labium vestibulare and the habenula
perforata, table 41, figure 10.
i cr\
loO
it
/
'-
a
: _
*
- v
/
^
.
-
/
>
\
_
-
-
140
A
it
*
k
;
^ -
- !
_-
:
/
/
12O
,*
\t\f\
y
~
~
1UO
1
Qf\
1
o-
~j
^
(
^
a-
-
ou
fj
i
g
/A-
f*f\
|
2
Y
25
50
Chart 18 The radial distance between labium vestibulare and the habenula
perforata according to the turns of the cochlea, table 41.
radial breadth from the labium vestibulare to the inner edge
of the head of the inner pillar cell, I have used, at earlier stages,
as in the preceding chapter, the same small prominence as an
inner fixed point (fig. 4). In table 44 (chart 19) are given the
values for this radial distance according to age. At the bottom
of the last column are given the ratios from 1 to 9, 1 to 546
72
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
TABLE 43
Distance between labium vestibulare and habenula perforata in n (Bottcher)
PLACE OF
CAT EMBRYO 9 CM.
CAT EMBRYO 11 .5
CAT THREE DAYS
ADULT CAT
MEASUREMENT
LONG
CM. LONG
OLD
I turn
120
120
120
100
II turn
130
130
130
110
III turn
150
140
140
130
TABLE 44
Radial distance between the labium veslibulare and the inner edge of the head of the
inner pillar cell on age (chart 19)
AGE
BODY WEIGHT
TURNS OF THE COCHLEA M
I
II
ill
IV
Average
days
grams
1
5
111
126
138
130
126
3
8
84
118
150
170
131
6
11
88
119
159
180
136
9
10
94
131
168
179
143
12
13
69
97
138
156
115
15
13!
",' 66
103
137
149
114
20
29
66
103
137
148
114
25
36
65
100
136
148
112
50
59
61
98
129
144
108
100
112
64
99
139
153
114
150
183
60
99
129
143
108
257
137
67
100
134
149
113
366
181
60
102
130
151
111
546
255
55 :..
99
128
143
106
Ratios 1 9 days
1546 "
12546 "
1.1
0.8
0.9
TABLE 45 Condensed
Ratios of the radial distance between the habenula perforata and the inner edge of
the head of the inner pillar cell according to the turns of
the cochlea on age
KATIOS BETWEEN TURNS
AVERAGE AGE
WEIGHT
I-II
I-HI
I-IV
days
grams
1
5
1 1.1
1 \.9
1 1.2
6
10
1.4
1.8
2.0
154
102
1.5
2.1
2.3
GROWTH OF THE INNER EAR OF ALBINO RAT
73
and 12 to 546 days of age. As the table shows, the values in-
crease in general from birth to nine days; therefore, the surface
of the greater epithelial thickening from the labium vestibulare
to its outer boundary becomes, during the earlier stage, wider
and wider, then decreases sharply, and after that continuously
but slowly. This sudden diminishing of the distance has a very
intimate relation with the change in the form of the papilla
spiralis at this stage of development.
This point I will discuss later.
That the values increase from the base to the apex first rapidly
and later less rapidly, is also to be seen here. Table 45 shows this
relation clearly. It is remarkable, however, that the ratio becomes
140
12O
1OO
AGE DAYS'
25
50 50 1OO 2OO 300 400 50O
Chart 19 The radial distance between the labium vestibulare and the
inner edge of the head of the inner pillar cell, table 44.
at each turn larger with age, although the absolute value is
after nine days generally smaller than at the preceding age.
Therefore, we see that the diminution of the distance after
nine days is largest in the basal turn and smallest in the apical.
Hensen ('63) asserts that there is a movement axialward of
the organ of Corti (resp. the head of the pillar cell), but gives no
measurements. Neither Bottcher nor Retzius measured this
distance. Prentiss ('13, page 445) states that "the distance
between the inner angle of the cochlea and the pillar cells, two
definite points, may be measured with considerable accuracy
and shows no important change in the position of the spiral
organ from the 13 cm. to the 18.5 cm. stage, nor later in the
new born animal" (pig) But he also does not record his meas-
urements.
74
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
Hardesty ('15, p. 54) says "that the space occupied by the
width of the greater epithelial ridge increases throughout the
coils of the cochlea up to pigs of 15 to 16 cm., and thereafter
it begins to decrease very perceptibly." He measured the
width ''from the membrana propria of the epithelium of the
greater ridge, at its most axial extension under Huschke's teeth,
to the apical end of the inner hair cell of the spiral organ. " The
TABLE 46
Vertical distance from the membrana basilaris to the surface of the pillar cells on
age (chart 20}
TURNS OF THE COCHLEA M
AGE
BODY WEIGHT
I
II
ill
IV
Average
days
grams
1
5
35
36
39
36
37
3
8
30
29
29
29
29
6
11
29
32
31
29
30
9
10
32
33
35
36
34
12
13
41
45
50
52
47
15
13
44
48
53
57
51
20
29
53
57
67
71
62
25
36
55
56
66
68
61
50
59
53
55
67
68
61
100
112
53
54
64
67
60
150
183
52
54
63
66
59
257
137
53
56
63
69
60
366
181
51
56
66
67
60
546
255
52
55
62
66
59
Ratios 1 12 days 1-1.3
1 20 " 1.7
1546 " 1.6
12546 " 13
20546 " 1.0
method of measurement differs from mine, so the results cannot
be compared directly. While the distance in the rat increases
to nine days of age, that in the pig decreases perceptibly in
fetuses more than 16 cm. long.
According to Hardesty ('15, p. 55). "the decrease in the I
and III half turns may be as much as one-third of the width
of the greater ridge when at its maximum size and activity. "
And "after the tectorial membrane is about completely produced,
GROWTH OF THE INNER EAR OF ALBINO RAT
75
and while the spiral organ is enlarging, the inner hair cells, and
therefore the organ, may be moved in the apical coil of the
cochlea axialward a distance of about half the maximum width
of the greater epithelial ridge, "
The differences of the values in the rat at 9 and 546 days are
in the basal and apical turn about the same, 39 and 36 n, res-
pectively (table 44). Thus while the inner edge of the inner
pillar cell approaches at 546 days in the basal turn by as much
as 41 per cent of the distance present at nine days, that in the
80
60
40
20
AGE.qAYS-
25 50 5Q 1QO 2OO 300 4OO 5OO
Chart 20 The vertical distance from the membrana basilaris to the surface
of the pillar cells, table 46, figure 1, 1-1.
apex moves only 20 per cent inward in old age. This result
is the reverse of that obtained in the pig by Hardesty. The
reason for this contradiction I will discuss later.
10. The vertical distance from the membrane basilaris to the
summit of the pillar cells. The method of getting the vertical
distance from the membrana basilaris to the surface of the
pillar cells is shown in figure 1, line 1-1. In table 46 (chart 20)
are given the values thus obtained. At the foot of the last
column are given the ratios of this distance at 1 to 12, 1 to 20,
1 to 546, 12 to 546, and 20 to 546 days. The average value is
relatively large at birth, it diminishes at three days, then increases
more rapidly to twenty days. After this it decreases very slowly.
The maximum height of the arch of Corti is at twenty days of
76
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
age. Comparing the values for the height in each turn, we find
that from nine days they increase from the basal to the apical
turn. This relation can be easily seen in table 47.
Retzius ( '84) gives in the rabbit and cat the following values
(table 48).
TABLE 47 Condensed
Ratios of the vertical distance from the membrana basilaris to the surface of the
pillar cells according to the turns of the cochlea
RATIOS BETWEEN TURNS
AVERAGE BODY
AVERAGE AGE
WEIGHT
I-II
i-ni
I-IV
days
grams
1
5
1 :1.0
1 : 1.1
1 : 1.0
1
11
: 1.1
: 1.1
: 1.1
18
21
: 1.1
: 1.2
: 1.3
213
138
: 1.0
: 1.2
: 1.3
TABLE 48
Vertical distance from the membrana basilaris to the summit of the pillar cells
BABBIT
CAT
Age
Basal
turn
Middle
turn
Apical
turn
Average
Basal
turn
Middle
turn
Apical
turn
Average
days
New-born
45
70
61
59
45
60
48
51
2
45
69
40
51
3
39
60
7
46
60
60
55
45
47
50
44
10
45
69
69
61
11
JK
50
60
42
51
14
45
57
66
56
30
' }'
33
51
57
47
Table 48 shows that the height of the arch of Corti in the
rabbit approximates that in the rat, though there are considerable
differences in the earlier stages. In the former the arch of Corti
develops after: birth only a little, and is therefore more pre-
cocious than in the rat. In the cat the same relation is to be
seen, but the absolute values in the latter animal are smaller
than in either the rabbit or the rat.
GROWTH OF THE INNER EAR OF ALBINO RAT 77
11. The greatest height of the tunnel of Corti. Some authors
have reported in several animals the appearance of the tunnel
of Corti just after birth, or even in later intrauterine life. In
the rat, however, it first appears through all the turns after
the ninth day. Sometimes we see it at nine days in the lower
turn, though not yet in the upper. The method of measuring
the height is shown in figure 1, line 1-1'. Table 49 (charts 21
and 22) gives the values for the greatest height of the tunnel of
Corti. At the foot of the last column are given the ratios from
12 to 25, 12 to 546, and 25 to 546 days.
As the table shows, the space appears in all the turns at twelve
days and has considerable height. This increases to twenty-five
days, than decreases very slowly. This increase and decrease
correspond to the changes in the distance of the summit of the
pillar cells from the basilar membrane.
When we consider the height in each coil of the cochlea, we
find the value increases from the base to the apex, first rapidly
then slowly. In table 50 this relation is clearly shown.
Retzius ('84) gives the values for the adult rabbit, man and
cat (one month) as follows (table 51).
According to this table, the average height is in the adult
man, cat, and rabbit somewhat less than in the rat.
12. The height of the papilla spiralis at the third series of
the outer hair cells. The measurements were taken along the
line 2-2 shown in figure 1. The growth of this vertical height
depends not only upon the increase of the length of the corre-
sponding outer hair cell, but chiefly upon the development of
the Deiters' cells, especially of the outermost row, and of the
sustentacular cells of Hensen.
In table 52 (charts 23 and 24) are given the values for this
vertical height of the papilla spiralis at the third series of the
outer hair cells according to age. At the bottom of the last
column are the ratios at 1 to 12, 1 to 20, 1 to 546, and 20 to 546
days. The heights decrease at three days, but increase from
nine to twelve days very rapidly, nearly doubling their minimal
values, and reach a maximum at twenty days. After that time
they decrease very gradually to the end of the record. There-
78
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
TABLE 49
Greatest height of the tunnel of Corti on age (charts 21 and 22}
AGE
BODY WEIGHT
TURNS OP THE COCHLEA M
I
II
ill
IV
Average
days
grams
1
5
3
8
6
11
9 1
10
12
13
29
33
39
37
35
15
13
31
34
42
46
38
20
29
37
42
52
56
47
25
36
39
41
54
56
48
50
59
38
41
53
57
47
100
112
38
43
51
56
47
150
183
37
41
49
54
45-
257
137
38
43
51
56
47
366
181
37
41
52
53
46
546
255
36
39
48
53
44
Ratios 12 25 days
12546 "
25546 "
1.4
1.3
0.9
1 In one case nine days old which could hear the space was found
through all the turns of the cochlea.
TABLE 50 Condensed
Ratios of the greatest height of the tunnel of Corti according to the turns of the
cochlea on age
, RATIOS BETWEEN TURNS
AVERAGE BOOT
AVERAGE AGE
WEIGHT
I-II
i-ni
I-IV
days
grams
12
13
1 : 1.1
1 1.3
1 1.3
18
21
:1.1
1.4
1.5
213
138
:1.1
1.3
1.4
TABLE 51
The greatest height of the tunnel of Corti in n (Retzius)
RABBIT
CAT (one month)
MAN
Basal
Middle
Apical
Aver-
age
Basal
Middle
Apical
Aver-
age
Basal
Middle
Apical
Aver-
age
30
39
36
35
18
37
36
30
28
45
49
41
GROWTH OF THE INNER EAR OF ZLBINO RAT
79
fore, the difference between the ratios at 1 to 20 and 1 to 546
days is very small.
At twelve days and after, the values for the height increase in
passing from the base to the apex, at first rapidly, then more
slowly. In the earlier stages this relation is obscure or reversed.
60
40
20
n
1
^
JS.
/
x
G
E
c
A
Y5-
25
50
5O 10O 20O 300 400 5OO
Chart 21 The greatest height of the tunnel of Corti, table 49, figure 1, 1-1
60
40
/(
^'
'
-
__ (
_
,
-
*
>
'
-
-
-
-
L-
^~"
1
a
-
/ -
n
A
>/c
u
Y
2
5
5
5<
D
II
~\c
J\.
)
2(
)C
)
3(
DC
)
4
4C
)0
5C
)0
Chart 22 The greatest height of the tunnel of Corti, according to the turns
of the cochlea, table 49. .
In the condensed table 53 are given the ratios in each turn.
While the ratio of each turn before eight days is about 1:1.1,
and between turns I and II remains constant in the later age,
that for I to III and I to IV is at 18 and 213 days decidedly
larger. Therefore, the increase of the height is most marked
in the III and IV turn, as shown in chart 24.
TABLE 52
Height of the papilla spiralis at the third series of outer hair cells on age
(charts 23 and 24)
AGE
BODY WEIGHT
TURNS OF THE COCHLEA M
I
II
III
IV
Average
days
grams
1
5
35
35
39
28
34
3
8
22
23
25
26
24
6
11
25
24
25
23
24
9
10
28
28
27
28
28
12
13
40
49
54
56
50
15
13
46
53
65
66
58
20
29
56
61
76
81
69
25
36
56
61
76
78
68
50
59
53
59
78
80
68
100
112
54
59
74
79
67
150
183
55
57
75
77
66
257
137
54
59
74
81
67
366
181
5?
58
75
78
66
546
255
52
58
72
75
64
Ratios 1 12 days 1 1.5
1 20 " 2.0
1546 " 1.9
20546 " 0.9
TABLE 53 Condensed
Ratios of the height of the papilla spiralis at the third series of outer hair cells
according to the turns of the cochlea on age
AVERAGE AGE
AVERAGE BODY
WEIGHT
BATIOS BETWEEN TURNS
I-II
i-ni
I-IV
days
grams
1
5
1 :1.0
1 :1.1
1 0.8
8
11
:1.1
: 1.1
1.1
18
21
: 1.1
: 1.4
1.5
213
138
: 1.1
:1.4
1.5
TABLE 54
Height of the papilla spiralis at the third scries of outer hair cells in n (Retzius)
BABBIT
CAT
AGE
Basal
turn
Middle
turn
Apical
turn
Average
Basal
turn
Middle
turn
Apical
turn
Average
days
New-born
48
70
60
59
45
60
45
50
2
45
70
54
56
3
40
58
7
54
69
66
63
42
5<
48
49
10
42
86
84
71
11
60
72
42
58
14
60
87
90
79
30
36
57
70
54
80
GROWTH OF THE INNER EAR OF ALBINO RAT
81
Retzius ('84) finds in the rabbit and cat the [values for this
height given in (table 54).
Comparing these average numbers with mine, it appears that
the height in the rabbit is greater, and in the cat smaller than
u
70
5O
30
10
k
AGE
o
25 5O 50 |OO 2OO 3OO 40O 5OO
Chart 23 The height of the papilla spiralis at the third series of the outer
hair cells, table 52, figure 1, 2-2.
90
70
50
30
10
AGE DA.YS-
O
25
50
5O 1OO 2OO 3OO 4OO 5OO
Chart 24 The height of the papilla spiralis at the third series of the outer
hair cells, according to the turns of the cochlea, table 52.
in the rat. In both animals the values increase rapidly at ten
to eleven days of age, as in the albino rat, but the height in these
animals is at the earlier stage almost twice as large as in the rat.
Hardesty ('15) measured the thickness of the organ of Corti in
82
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
the pig in a somewhat different way, using the vertical line from
the basilar membrane proper through the m'ddle of the outer
hair cell to the surface of the organ, and found the increase in
thickness to take place most rapidly at the stages before full term,
though it seems to continue after birth. I have not made cor-
TABLE 55
Greatest height of Hensen's supporting cells on age (chart 25)
AGE
BODY WEIGHT
TURNS OP THE COCHLEA M
1
II
III
IV
Average
days
grams
I
5
36
36
38
31
35
3
8
18
21
21
24
21
6
11
21
20
21
18
20
9
10
20
23
23
24
23
12
13
40
49
56
58
51
15
13
44
56
69
72
60
20
29
64
64
86
87
75
25
36
69
71
84
86
78
50
59
71
74
87
89
81
100
112
77
. 78
87
89
83
150
183
76
77
<3
93-
85-
257
137
81
83
89
89
86
366
181
82
83
89
91
86
546
255
79
79
92
93
86
Ratios 1 6 days
1 12
1 20
1546
6 12
6 20
6546
12 20
12546
20546
0.6
1.5
2.1
2.5
2.6
3.8
4.3
1.5
1.7
1.1
responding studies on the rat. In the latter animal, however,
the rapid increase usually appears at twelve days of age, when
the animal as a rule first responds to auditory stimuli, and thus
we have a correlation between the development of the organ
and the beginning of the function, which will be discussed later.
In the case of one rat that could hear at nine days this change
had already occurred.
GROWTH OF THE INNER EAR OF ALBINO RAT
83
13. The greatest height of Hensen's supporting cells. The older
authors (Kolliker and others) thought that the arch of Corti
marks the highest point of the papilla which slopes from this
point gradually outward to the cells of the zona pectinata.
Against this erroneous idea Hensen ('63) first published obser-
vations showing that the highest point is in the papilla which
ascends laterally from the outer hair cells, and then slopes
abruptly and passes over to the cells of the sulcus spiralis externus.
We term this prominence Hensen's prominence and the cells,
Hensen's supporting cells. The measurements of the height of
90
M
70
50
30
\c\
.-<
-
s
l
1
/
1
/
I'
i
1
|
\
j
\
1
\
jj
GE
i
T
25 50 50 100 200 300 400 50O
Chart 25 The greatest height of Hensen's supporting cells, table 55.
these cells were made along 3 3 in figure 1. Table 55 (chart
25) shows the values for the greatest vertical height of these
supporting cells according to age. At the foot of the last column
are given the ratios from 1 to 6, 1 to 12, 1 to 20, 1 to 546, 6 to 12,
6 to 20, 6 to 546, 12 to 20, 12 to 546, and 20 to 546 days. The
values diminish at the earlier stage from birth to six or nine days.
At twelve days they increase suddenly, more than doubling.
After that they increase to old age, rapidly up to twenty days
and then slowly. Here also the height increases from the base
to the apex, the most marked increase occurring between turns
II and III. In table 56 this relation is clearly shown. Retzius
('84) gets values of this height in the rabbit and cat as follows
(table 57).
84 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
In both the rabbit and the cat the height increases at ten to
eleven days very considerably, as it does in the rat. Only
there is a large difference in the absolute values for the
three animals, these being largest in the rabbit and smallest
in the cat. The final average values in the cat are nearly the
same as those in the rat at the same age.
Kolmer ('07) finds in the calf the value in the highest point
of the organ of Corti in the region of the innermost Hensen's
cells as follows:
In the basal turn, 84 [A
In the second turn, 90 JJL
In the third turn, 105 [JL
Average, 93 [i.
Hensen ('63) gives in man the average height of the papilla
as 90 (JL in the hamulus and 60 [j. in the radix. Thus the height
of Hensen's cells is different in different animals.
When we consider the growth in the height of Hensen's cells
we can picture the change of the form in the papilla spiralis.
As shown already, the height of the pillar cells is largest at the
earlier stage, when the papilla has its highest point at the summit
of the arch of Corti, and slopes downward to the Hensen's cells.
But at twelve days the form is reversed, and the highest point
is in Hensen's prominence from which the surface slopes inward
more or less steeply to the surface of the pillar cells and the
inner supporting cells. Thus the surface of the papilla does
not run parallel to the basilar membrane, but makes with it a
sharp angle opening outward. This angle has been measured.
14- The angle subtended by the extension of the surface of the
lamina relicularis with the extended plane of the membrana basilaris.
As just stated, the lamina reticularis after the earlier stages
is not parallel to the membrana basilaris, but forms an angle
with it. The measurements of this angle , were taken as
shown in lines 4~4' i n figure 1. In table 58 (chart 26) are given
the values for the angle in degrees. Before nine days there is
no appreciable angle. From twelve to twenty days the angle
increases rather rapidly, and after twenty days continuously
but slowly. The ratio at the bottom of the last column shows
this clearly.
GROWTH OF THE INNER EAR OF ALBINO RAT
85
Comparing the values of the angle in each turn according to
age, there is no clear evidence that it increases from base to apex,
though it tends to be largest in turn III and next largest in turn
II. The condensed table 59 shows these relations. Retzius
( ; 84) finds this angle in the rabbit and cat to be as in table 60.
TABLE 56 Condensed
Ratios of the greatest height of Hensen's supporting cells according to the turns of
the cochlea
RATIOS BETWEEN SUCCESSIVE TURNS
AVERAGE AGE
AVERAGE BODY
WEIGHT
1
I-II
I-III
I-IV
days
grams
1
5
1 1.0
1 1.1
1 0.9
8
11
1.1
1.2
1.2
18
21
1.1
1.4
1.5
213
138
1.0
1.2
1.2
TABLE 57
Greatest height of Hensen's supporting cells in M (Retzius)
RABBIT
CAT
Age
Days
Basal
turn
Middle
Apical
Average
Basal
Middle
Apical
Aver-
age
Xew-born
38?
60?
50?
49?
45
50
39
45
2
55?
60?
3
39
54
7
48
81
67
65
57
50
40
49
10
105
125
105
112
11
75
78
45
66
14
150
120
30
50
69
95
71
Retzius also finds in man in the basal turn 25, in the middle
35, and in the apical 23. Thus the angle always increases with
age, but has different absolute values in different mammals and
always tends to be greater in the middle turns.
15. Lengths of the inner and outer pillar cells. The measure-
ments of length were taken as shown by lines 1-1, and 2-2 as in
figure 2. This does not give the total length, but the length
from the base to the point, just below the joint. As is well
86
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
TABLE 58
Angle of the lamina reticularis with the plane of Ihe membrana basilaris in
degrees, 6 (chart 26}
TURNS OF THE COCHLEA DEGREES
AGE
BODY WEIGHT
I
II
III
IV
Average
days
grams
1
5
3
8
6
11
9
10
12
13
7
12
13
9
10
15
13
11
14
13
13
13
20
29
15
13
11
11
13
25
36
14
14
13
13
14
50
59
15
15
17
11
15
100
112
15
14
16
14
15
150
183
15
15
19
17
17
257
137
13
15
18
17
16
366
181
16
15
16
16
16
546
255
16
16
17
17
17
Vertical averages
13.7
14.3
15.3
13.8
Ratios 12 20 days 1 : 1.3
12546 " :1.7
TABLE 59 Condensed
Ratios of the angle of the lamina reticularis with the plane of the membrana basilaris
according to the turns of the cochlea
RATIOS BETWEEN TURNS
AVERAGE AGE
AVERVGE BODY
WEIGHT
I-II
I-II I
I- IV
days
12
grams
13
1 1.7
1 1.9
1 : 1.3
18
21
1.0
0.9
:0.9
213
138
1.0
1.2
:1.0
TABLE 60
Angle of the lamina reticutaris with the plane of the membrana basilaris in degrees
(Retzius)
Age
Basal
turn
Middle
turn
Apical
turn
Average
Basal
turn
Middle
turn
Apical
turn
Average
days
New-born
5?
8?
5? 8?
2
3
5? 8?
7
17
19
11
5
5
10
10
20
30
23
24
11
20
1020
14
25
50
45
40
30
18
23
20
20
GROWTH OF THE INNER EAR OF ALBINO RAT
87
known, the inner and outer pillar cells when mature show a more
or less S-shaped curvature, though they are straighter in the
earlier stages. Thus the length as measured in the adult cochlea
is somewhat smaller than the natural lengths.
DEGREES
18
15
12
25
50
5O 1OO 20O 300 40O 500
Chart 26 The angle subtended by the extension of the lamina relicularis
with the extended plane of the membrana basilaris, in degrees, table 58, fieure 1
4-4', 9-
In table 61 (charts 27 to 32) is given the values for the lengths
of the inner and outer pillar cells according to age. At first we
shall consider the average values for the length of the inner
and outer pillar cells taken together. This length diminishes
at three days. From three to twelve days it increases rapidly,
88
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
and from twelve to twenty days more slowly. After twenty
days it decreases a little. The ratios at the bottom of the last
column show these relations. The familiar fact, that the length
increases from the base to the apex is clearly shown in chart 28.
TABLE 61
Lengths of the inner and outer pillar cells (without head) measured from the footplate
on the membrana basilaris to the point directly below the junction
(charts 27 to 32)
AOE
BODY
WEIGHT
INNER PILLAR
OUTER PILLAR
Com-
bined
Average
Turns of the cochlea M
Turns of the cochlea M
I
II
ill
IV
Average
I
II ill
IV
Average
days
gms
1
5
28
29
29
29
29
24
27
27
26
26
28
3
8
26
23
26
23
25
19
20
20
21
20
23
6
11
35
36
36
37
36
21
26
27
26
25
31
9
10
35
39
41
40
39
26
26
29
29
28
34
12
13
33
38
44
44
40
46
59
72
72
62
51
15
13
34
38
48
51
43
44
59
74
78
64
54
20
29
43
47
56
60
52
56
65
79
83
71
62
25
36
43
47
56
60
52
53
64
80
84
70
61
50
59
42
44
55
61
51
52
64
79
84
70
*61
100
112
42
44
53
58
49
52
62
79
84
69
59
150
183
41
43
54
59
49
51
64
76
85
69
59
257
137
40
44
53
60
49
53
64
75
85
69
59
366
181
39
45
53
59
48
50
64
78
83
69
59
546
255
41
44
53
58
49
49
64
78
83
69
59
Ratios 1- 12 days
1 1.4
1 :2.4
1 : 1.8
1- 20 "
1.8
2.7
:2.2
1-546 "
1.7
2.7
:2.1
20-546 "
0.9
1.0
: 1.0
When we calculate the average values of the inner and outer
pillar cells from Retzius table ('84), we get the following (table
62). .
TABLE 62
Combined lengths of the inner and outer pillars from the foot plate to a point
directly below the junction in n (Retzius)
RABBIT (adult)
CAT (adult)
MAN (adult)
Basal
turn
Middle
turn
Apical
turn
Aver-
age
turn
Basal
turn
Middle
turn
Apical
turn
Aver-
age
Basal
turn
Middle
turn
Apical
turn
Aver-
age
66
85
78
76
55
75
73
67
55
84
87
75
GROWTH OF THE INNER EAR OF ALBINO RAT
89
70
50
30
10
25
50
5O 1OO 2OO 300 4OO 5OO
Chart 27 The length of inner and outer pillar cells combined, without
head, measured from the foot plate on the membrana basilaris to the point
directly below the junction, table 61, figure 2, /-/, 2-2.
80
w.q A re
25 50 50 JOO 200 300 4OO 5OO
Chart 28 The length of inner and outer pillar cells combined, without
head, measured from the foot plate on the membrana basilaris to the point
directly below the junction, according to the turns of the cochlea, table 61.
,u
50
30
in
s
r -'
J
GE
D
A
TO
25
5O
2OO
5(X)
Chart 29 The length of inner pillar cell without head, table 61, figure 2, 1-1.
90 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
As table 62 shows, the values in these mammals are larger
than those in the albino rat a result which fits with our previous
observations.
When we consider the length of the inner pillar cells alone,
we see that the values (chart 29) here also increases from three
days to twenty days, but not so largely as in the combined values
of the inner and outer pillar cells. After twenty days the values
for the inner pillar cells decrease slightly. This relation is shown
by the ratios at the bottom of the corresponding column. That
the increase progresses from the base to the apex, being most
marked in turn III, is illustrated in chart 30. The condensed
table 63 shows those relations also. The one-day-old rat is an
exception.
We turn now to the growth in the length of the outer pillar
cells. As we see in table 61 (chart 31), the length of the outer
pillar cell does not increase so much from one to nine days as the
inner pillar cell did. At twelve days, however, the increase in
length is very marked, that is, 2.2 times as much as at nine days.
After the outer pillar cell reaches its maximum at twenty
days, it decreases only slightly with advancing age. The ratios
at the bottom of the corresponding column show this relation
clearly. The length increases from base to apex, though this
relation is not well established until twelve days, as shown in
table 61 and chart 32. The ratios of the outer pillar cells ac-
cording to the turns of the cochlea are shown in table 64.
The inner and outer pillar cells show marked differences in
their growth. While at the earlier ages the length of the inner
is greater than that of the outer, yet after twelve days this
relation is reversed. Moreover, from nine to twelve days the
growth is gradual in the inner pillar cells, but rapid in the outer.
The condensed table 65 shows the values for the length of the
inner and outer pillar cells separately. In the last column are
given the ratios between them.
In the accompanying table 66 I have compared the values
obtained in the rat with those given by other authors.
As table 66 shows, the absolute values differ in various animals.
However, the ratios between the values for the inner and outer
eu
A*
fir\
ou
/
,
k- -
2
{/
""
-
-
:,
-
A f\
i
j'f
-
,
=-fl
*HJ
A
-X-
v
J-
*-i
O/"
i
20
ft
p
IT
L
P
L
ft
vcj-
f\
u
2
o
25
50 50 10O 200 3OO 4OO 50O
Chart 30 The length of the inner pillar cell without head, according to
the turns of the cochlea, table 61.
80
M
60
40
20
f\
/
f-'
1
1
1
1
,
.
.'"1
\
AGE
i i
DAY
25
50
5O 1OO 200 300 4OO 50O
Chart 31 The length of outer pillar cells without head, table 61, figure 2,
IVAJ
M
RH
t
ou
y
~
"~
^
^
ar\
/
*
^
~-
~
^
^
~
* *
"'
"~
" *
oU
<k "
k <
~^
_,
>
_
*
-~
Af\
;
n
t *
oo
^U
r
<~~
A
k/C
n
(j
1OT
25 50 50 1OO -OO 3OO 4OO 5OO
Chart 32 The length of outer pillar cells without head, according to the
turns of the cochlea, table 61.
91
92
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
TABLE 63 Condensed
Ratios of the length of the inner pillar cells according to the turns of the cochlea
AVERAGE AGE
AVERAGE BOOT
WEIGHT
RATIOS BETWEEN TURNS
I-II
I-II I
I-IV
days
1
grams
5
1 1.0
1 1.0
1 1.0
8
11
1.1
1.2
1.1
18
21
1.1
1.3
1.4
213
138
1.1
1.3
1.4
TABLE 64 Condensed
Ratios of the length of the outer pillar cells according to the turns of the cochlea
AVERAGE AGE
AVERAGE BODY
WEIGHT
RATIOS
BETWEEN TURNS
I-II
I-II I
I- IV
days
1
grams
5
1 : 1.1
1 1.1
1 1.0
8
11
:1.2
1.3
1.3
18
21
: 1.2
1.5
1.6
213
138
: 1.3
1.5
1.6
TABLE 65 Condensed
Comparison of the average length of the inner and outer pillar-cellswithout
head.
AVERAGE LENGTH OF PILLAR CELLS
AVERAGE AGE
AVERAGE BODY
WITHOUT HEAD
RATIOS OF INNER
\V V T ( ' H T
TO OUTER
Inner
Outer
days
grams
1
5
29
26
1 :1.0
8
11
35
34
:1.0
18
21
48
68
:1.4
213
13S
50
69.
: 1.4
pillar cells are smallest in man and in the rat and alike in the
other two forms, Retzius ('84). Hensen ('63) states that in the
base of the human cochlea both pillar cells are equally long.
Later, Pritchard ('78) supported this observation. In the
literature, however, no one except these two authors report the
inner and outer pillar cells in the base of the adult cochlea as
equal in length, but the inner is always stated to be shorter than
the outer. We may therefore say that most authors agree that
the inner pillar cells are at earlier stages longer than the outer,
then they become equal, and finally the outer surpass the inner.
GROWTH OF THE INNER EAR OF ALfcINO RAT
93
TABLE 66
Lengths of inner and outer pillars in several mammals according to different authors.
Measurements in n
INNER PILLAR
OUTER PILLAR
Authors
Animals
Basal
turn
Mid-
dle
Apical
Av.
B.
M.
A.
Av.
Ratio
Corti
Mam-
mals
30
30
34
31
45-
49
54-
58
69
57
1:1.8
Hen-
sen
Man
48
86
(Hamul-
us)
48
98
(Hamul-
us)
Ret-
zius
Wada
Rabbit
56
60
60
59
75
110
95
93
:l.
Cat
41
54
57
51
68
62
95
89
84
:1.6
Man
48
68
70
62
100
103
88
:l.t
Albino
rat
after 20
days
I
41
II
45
III
54
IV
59
50
I
52
II
64
III
78
IV
84
70
-.1.4
16. Inner and outer hair cells. For a long time the inner
and the outer hair cells have been regarded as the most important
elements in the papilla spiralis. As these sense cells have a
delicate histological structure which is readily altered, the
systematic study of their growth, especially after the appearance
of hearing, is a difficult matter. Though there are some observations
on the length of these cells, detailed studies on their growth
have not been made heretofore. I have therefore endeavored
to follow the changes of their size during the postnatal period.
It is first necessary to determine the form of these cells. They
are generally described as cylindrical, but this description is
inexact. Moreover, the inner and outer hair cells are somewhat
different in shape. The former has on the surface a large oval
terminal disk, which is wide hi the spiral and narrow in the
radial direction. This narrows downwards to a thinner neck
which expands into the broader body and terminates in a more
or less round but somewhat pointed irregular end.
94
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
1600
y
1400
1200
1000
800
600
400
2OO
^
/
V
-^
^
^e
=.
'
^
.
k
**
\
i
i
|
i
i
-I
-
-1
_ ._ .<
4
GE
E
A
^S
ft
25
50
5O 100 2OO 300 4OO 5OO
Chart 33 The weighted volume of inner and outer hair cells combined,
and of their nuclei in cubic micra, tables 67 and 69.
- Weighted volume of inner and outer hair cells combined.
Weighted volume of nuclei of inner and outer hair cells combined.
The outer hair cells have a much more cylindrical form,
their upper terminal disk is not so wide and not round, but
hexagonal. They become a bit thin in the neck, then wide in
the body. Their lower end is rounded. In order, however, to
determine the cell volume, the cell form has been taken as that
of a cylinder. For computation, the average of the diameters
measured in three places, the end disk, neck, and cell body, was
taken as the diameter and the length of the cell as the length of
the cylinder. From these data the volume of the cylinder was
computed.
GROWTH OF THE INNER EAR OF ALBINO RAT
95
In table 67 are given the values for the volume of the cell
bodies in the (1) inner and (3) outer hair cells separately and
the weighted volume of both cells (in the radial section of the
rat cochlea we see one row of inner and three rows of outer
hair cells), according to age.
TABLE 67
Average volumes of the inner and outer hair cells in cubic micro
(charts 33 to 37)
AGE
INNER HAIR CELL
OUTER HAIR CELL
BODY
WGHt
Tu
I
rns of
II
the o
III
achlea
IV
fit
Average
T
I
urns o
II
f the (
III
iwlilr;
IV
l M 3
Average
WEIOHTD
AVERAGE
VOLUME
days
1
gms
5
1255
982
832
631
925
641
626
505
359
533
631
3
6
' 9
12
15
20
8
11
10
13
13
29
1457
1374
1451
1553
1598
1627
1367
1451
1734
1812
1618
1764
1206
1549
1994
1910
1902
1972
913
1221
2013
2157
2128
2189
1236
1399
1798
1858
1812
1888
767
1047
914
818
815
894
928
967
1308
1210
1178
1215
867
1053
1459
1602
1595
1606
571
800
14^8
1499
1559
1960
783
967
1277
1282
1287
1419
896
1075
1407
1426
1418
1536
1293
Av. 11
14
1510
1624
1756
1770
1665
876
1134
1364
1303
1169
25
50
100
150
257
366
546
36
59
112
183
137
181
255
1540
1497
1353
1362
1345
1290
1266
1655
1611
1550
1497
1524
1561
1486
1909
1821
1744
1683
1738
1817
1772
1995
1924
2018
1917
1976
2297
2257
1775
1713
1666
1615
1646
1741
1695
834
805
837
832
873
893
831
1243
1204
1306
1150
1230
1239
1336
1539
1580
1510
1803
1555
1651
1650
1702
1906
1737
1917
1927
1844
1839
1330
1374
1348
1426
1396
1407
1414
1441
1459
1428
1473
1459
1491
1484
Av. 213
138
1379
1555
1783
2055
1693
844
1244
1613
1839
1385
1462
Ratios 1- 12 days
1- 20 "
1-546 "
20-546 "
1- 11 "
11-213 "
1 :2.0
:2.0
0^9
1 :2.4
:2.7
:2.7
:2!2
1 :2.3
:2.4
:2.4
:0.9
:2.0
At first we shall consider the weighted volume for the cell
bodies of the inner and outer hair cells combined (chart 33).
As table 67 shows, the volume increases continuously to the full
size at twenty days. From one to twelve days the increase is
rapid, and after that the volumes are about the same, though
somewhat fluctuating. The ratios show this relation clearly.
96
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
Condensing all age groups into three (averages in table -67),
then the relation changes somewhat. From one to eleven days
the volume increases more than 100 per cent, while from eleven
to 213 days it increases only 13 per cent.
JUUO
1800
1600
1400
1200
10OO
800
6OO
4OO
200
O
f
[
i
\
^_
,
*^
^
"*
.
-M.
-"-
^--
-
-
4*
X"
**
*
^
- <
r
j
fl
I
^
**'
~~
,
.
~-
-
-
-
"'
...
c
A
YS-
25 5O 50 1OQ 2OO 300 400 500
Chart 34 The volume of inner hair cells and of their nuclei, tables 67 and 69.
Volume of inner hair cells.
Volume of nuclei of inner hair cells.
The data for the growth of the nuclei of the inner and outer
hair cells are presented in tables 68 and 69. The weighted
values for the diameters of the nuclei (table 68) are large at
the earlier stages, but from twelve days decrease gradually till
GROWTH OF THE INNER EAR OF ALBINO RAT
97
old age. In the three condensed age groups (averages) we see
the decrease of the values from birth till old age. In table 69
are given the values for the volumes of the nuclei, calculated
as spheres (chart 33).
M*
1600
10OO
600
400
V
AGEjDAYS-
25
50 50
2OO 3OO 400 500
Chart 35 The volume of inner hair cells, according to the turns of the
cochlea, table 67.
98
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
The weighted values for the volumes of the inner and outer
hair cells in each turn are given in [A 3 table 70. At the bottom
of each column is given the ratio from 1 to 12, 1 to 20, 1 to 546,
and 20 to 546 days of age. While the volume at birth is largest
in turn I and smallest in turn IV, that in turn III is largest at
10UU
y
1400
1200
1OOO
800
60O
4OO
200
n
P*.
*^
=
MI
r
_
=
Li.
. 1
i
\
ir -<-<
- ,
X
/
--
-
/
K
f
1
1
;
/
/
1
f-
-
\
**'
1
j
.,
L_
_.
_
_
-
._
-
_
&
E
C
)A
YS-
/
25 50 50 1OO 2OO 3OO 400 500
Chart 36 The volume of outer hair cells and of their nuclei, in cubic micra,
tables 67 and 69.
Volume of outer hair cells.
._. Volume of nuclei of outer hair cells.
six days. After nine days the volume increases always from base
to apex.
Comparing the weighted vo'ume in each turn according to
age, we find that the rate of increase in volume is smallest in
turn I (1.3 to 1.2) and largest in turn IV (3.9 to 4.6) (table 70).
In table 72 are given the weighted values for the diameters
of the nuclei of the inner and outer hair cells in each turn. They
GROWTH OF THE INNER EAR OF ALBINO RAT
99
increase and then decrease during the first twelve days. The rate of
decrease is largest in turn I, and smallest in turn IV, as the ratios
at the bottom of each column show. That the diameters at
2000
1800
1600
1400
1200
1000
800
600
400
200
A
.
.
i.
.
',
'
-
.
.
,
!
*
' 1
J
'
.
,
I
\
.
.
i
s
1
>,
1
*s
-^
\
1
N
I
's.
^
.
X
1
4
s
\
j
'
""^
X 1
1
^
~*
\
,
i>
,.'
01
f
/
\
---
^
--
f^
B
H.
-
m
-
.
=:
~t ~
OH
*
~<
-
^
*
.
j
t
A
^GE DAVs-
i i i i i
25
50
5O 1OO 2OO 30O 40O 5OO
Chart 37 The volume of outer hair cells, according to the turns of the
cochlea, table 67.
the later ages have about the same value in each turn, or are a
little larger in the upper than in the lower turn, is to be seen
in table 73.
TABLE 68
Mean diameters of the nuclei of the inner and outer hair cells in M
DIAMETERS NUCLEI OF THE
DIAMETERS NUCLEI OF THE
INNER HAIR CELLS
OUTER HAIR CELLS
WEIGHT-
AGE
BODY
wght
Turns of the cochlea ju
Turns of the cochlea M
ED
AVERAGE
I
II
ill
IV
Average
I
II
ill
IV
Average
days
gms.
1
5
8.6
8.3
7.8
7.8
8.1
7.7
8.1
7.4
7.6
7.7
7.8
3
8
8.6
8.5
8.2
7.8
8.3
8.3
8.4
8.J
7.5
8.1
8.2
6
11
8.5
8.6
8.3
8.0
8.3
8.0
8.0
8.1
7.9
8.0
8.1
c
10
8.7
8.5
8.2
8.7
8.5
76
7.9
8.4
8.2
8.0
8.1
12
13
7.6
7.7
7.5
7.9
7.7
5.8
6.5
6.8
7.4
6.6
6.9
15
13
7.5
7.5
7.7
7.9
7.6
6 1
6.6
6.8
7.0
6.6
6.9
20
29
7.0
7.3
7.6
7.8
7.4
6.0
6.4
6.9
7.3
6.6
6.8
Av. 11
14
8.0
8.0
7.9
8.0
8.0
7.0
7.3
7.5
7.6
7.3
7.5
25
36
7.3
7 2
7.2
7.1
7.2
6.0
6.3
6.3
6.5
6.3
6.5
50
59
7.0
75
7.3
7.3
7.3
6.0
6.2
6.3
6.7
6.3
6.6
100
112
6.7
7.0
7.1
7 1
7.0
5.8
6.0
6.0
6.0
5.9
6.2
150
183
6.6
6.8
7.0
7.3
6.9
6.0
6.0
6.2
6.1
6.0
6.2
257
137
6.6
6.9
7.0
7.7
7.0
5.9 16.0
6.2
6.4
6.1
6.3
366
181
7.6
7.4
7.3
7.2
7.4
5.9
6.0
6.1
6.0
6.0
6.4
546
255
6.5
6.5
6.5
7.1
6.6
5.8
6.0
6.1
6.4
6.1
62
Av. 213! 138
6.9
7.0
71
7.3
7.1
5.9
6.1
6.2
6.3
6.1
6.3
Ratios 1- 12 days
1:1. 0,|
1 :0.9|| 1 :0.9
1- 20 "
:0.9
:0.9 :0.9
1-546 "
:0.8
:O.S 0.8
20-546 "
:0.9 |
:0.9 :0.9
TABLE 69
Average volumes of the nuclei of the inner and outer hair cells (charts 33, 34 and 36)
AGE
BODY WEIGHT
VOLUME OF NUCLEUS HAIR CELLS
Inner Outer
WEIGHTED
VOLUMES
INNER AND OUTER
HAIR CELLS
days
gms.
M'
M
M 3
1
5
278
239
248
3
8
299
278
289
6
11
299
268
278
9
10
322
268
278
12
13
239
151
172
15
13
230
151
172
20
29
212
151
165
25
36
195
131
144
50
59
204
131
151
100
112
180
108
125
150
183
172
113
125
257
137
180
119
131
366
181
212
113
137
546
255
151
119
125
Ratios 1- 12 days
1- 20 "
1-546 "
20-546 "
1 :0.9
:0.8
:0.5
:0.7
:0.6
:0.6
:0.5
:0.8
:0.7
:0.7
:0.5
:0.8
100
GROWTH OF THE INNER EAR OF ALBINO RAT
101
The growth of the inner hair cell. The volume of the inner
hair cell table 67 (chart 34) increases with age up to twenty
TABLE 70
Weighted volumes of the inner and outer hair cells according to the turns of the
cochlea
AGE
BODY WEIGHT
TURNS OF THE COCHLEA M*
I
II
ill
IV
days
gms.
1
5
795
715
587
427
3
8
940
1038
952
657
6
11
1129
1088
1177
905
9
10
1048
1415
1593
1574
12
13
1002
1361
1679
1664
15
13
1011
1288
1672
1701
20
29
1052
1352
1698
2017
25
36
1011
1346
1632
1775
50
59
978
1306
1640
1911
100
112
966
1367
'1569
1807
150
183
965
1237
1773
1917
257
137
991
1304
1601
1939
366
181
992
1320
1693
1957
546
255
940
1374
1681
1944
Ratios 1- 12 days
1 : 1.3 1
1.9
1 :2.9
1 :3 9
1- 20 "
:1.3
1.9
:2.9
:4.7
1-546 "
: 1.2
1.9
:2.9
:4.6
20-546 "
:0.9
1.0
:1.0
:1.0
TABLE 71 Condensed
Ratios of the weighted volumes of the inner -and outer hair cells according to the turns
of the cochlea
BATI08 BETWEEN TURNS
AGE
BODY WEIGHT
I-II
i-ni
I-IV
days
0ms.
1
5
1 :0.9
1 :0.7
1 :0.5
8
11
:1.2
:1.3
:1.2
18
21
:1.3
: 1.6
: 1.8
213
138
:1.4
:1.7
:1.9
days; to nine days rapidly, then slowly. After twenty days it
decreases slowly, as do the weighted volumes of the inner and
outer hair cells, and with fluctuations, is nearly the same after
102
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
100 days. The three condensed age groups show that from
1 to 11 days it has increased 80 per cent, while from 11 to 213
days it has gained less than 2 per cent.
TABLE 72
Weighted diameters of the nuclei of the inner and outer hair cells according to the
turns of the cochlea
AGE
BODY WEIGHT
TURNS OF THE COCHLEA M
I
II
ill
IV
days
gms.
1
5
7.9
8.2
7.5
7.7
3
8
8.4
8.4
8.1
7.6
6
11
8.1
8.2
8.2
7.9
9
10
7.9
8.1
8.4
8.3
12
13
6.3
6.8
7.0
7.5
15
13
6.5
6.8
7.0
7.2
20
29
6.3
6.6
7.1
7.4
25
36
6.3
6.5
6.5
6.7
50
59
6.3
6.5
6.6
6.9
100
112
6.0
6.3
6.3
6.3
150
183
6.2
6.2
6.4
6.4
257
137
6.1
6.2
6.4
6.7
366
181
6.3
6.4
6.4
6.3
546
255
6.0
6.1
6.2
6.6
Ratios 1- 12 days
1 :0.8
1 :0.8
1 :0.9 1
1.0
1- 20 "
:0.8
:0.8
:0.9
1.0
1-546 "
:0.8
:0.7
:0.8
0.9
20-546 "
: 1.0
:0.9
:0.9
0.9
TABLE 73. Condensed
Ratios of the weighted diameters of the nuclei of the inner and outer hair cells
according to the turns of the cochlea
RATIOS BETWEEN TURNS
AVERAGE AGE
AVERAGE BODY
WEIGHT
I-II
i-m
I-IV
days
gms.
1
5
1 :1.0
1 0.9
1 1.0
8
11
:1.0
1.0
1.0
18
21
:1.0
1.1
1.1
213
138
:1.0
1.0
1.1
From nine days on the volume of the inner hair cell increases
in passing from the base to the apex. During the earlier stages
GROWTH OF THE INNER EAR OF ALBINO RAT
103
there are some fluctuations (table 67, chart 35). In the con-
densed table 74 the general relations are shown. The growth
of the nuclei of the inner hair cells in diameter is given in table 68.
As we see, the diameters increase from birth to nine days,
then decrease slowly but steadily. In the three average age
groups, however, the values decrease continuously with age.
In table 69 are given the values for the volumes of the nuclei
of the inner hair cell (chart 34).
TABLE 74 Condensed
Ratios of the volume of the inner hair cells according to the turns of the cochlea
RATIOS BETWEEN TURNS
AVERAGE AGE
AVERAGE BODY
WEIGHT
I-II
i-in
I-IV
days
grams
1
5
1 0.8
1 0.7
1 0.5
11
14
1.1
1.2
1.2
213
138
1.1
1.3
1.5
TABLE 75 Condensed
Ratios of the diameters of the nuclei of the inner hair cells according to the turns of
the cochlea
RATIOS BETWEEN TDRN8
AVERAGE AGE
AVERAGE BODY
WEIGHT
I-II
I-II I
I-IV
days
grams
1
5
1 1.0
1 :0.9
1 0.9
11
14
1.0
:1.0
1.0
213
138
1.0
:1.0
1.1
The ratios of the diameters of the nuclei of the inner hair
cells decrease at the earlier ages in each turn from the base to
the apex. After nine days they are nearly the same in all the
turns (tables 68 and 75), though their absolute values decrease
in all the turns after nine days.
The growth of the outer hair cells. In general, the changes in
the volume of the outer hair cells are like those in the inner
hair cells. Therefore, the volume increases strikingly up to nine
days of age, then gradually to twenty days. The main dif-
104
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
ference is that the volume in the outer hair cells does not diminish
so much after twenty-five days, but holds nearly the same value
(table 67, chart 36). In condensed age groups, therefore, we see
a large increase in the size of the cells with age.
To determine the growth of the outer hair cells in each turn
of the cochlea, table 67 is used (chart 37). From twenty days on
the values increase from the basal to the apical turn. Before
twenty days the relations are irregular or reversed. In table
76 this relation is clearly brought out.
Comparing the changes of the volume of the outer hair cells
in three age groups (table 67), we find that the average volume
increases throughout each turn with age, except in turn I, where
TABLE 76 Condensed
Ratios of the volumes of the outer hair cells according to the turns of the cochlea
RATIOS BETWEEN TURNS
AVERAGE AGE
AVERAGE BODY
WEIGHT
I-II
i-in
I-IV
days
grams
1
5
1 1.0
1 0.8
1 0.6
11
14
1.3
1.6
1.5
213
138
1.5
1.9
2.2
that at eleven days is largest. In the inner hair cells, however,
values at eleven days are largest in both turn I and II.
For the nuclei of the outer hair cells, the diameters are given
in table 68). Here the d ! ameters tend to increase from one to
nine days. At twelve days they decrease strikingly, and after
that very slowly. In table 69 are given the values for the volumes
of the nuclei of the outer hair cells.
In table 68 are given also the measurements for the nuclei
of the outer hair cells according to the turn of the cochlea.
At nine days and after, the diameters become larger in passing
from base to apex, while in the earlier stages this relation is
irregular or reversed. The decrease of the measurements in,
each turn with age is clearly shown in the three age groups.
GROWTH OF THE INNER EAR OF ALBINO RAT
105
In table 77 are given the average ratios of turn I to the three
other turns.
The comparison of the growth of the inner and outer hair
cells. As already stated, the growth of the inner and outer hair
.cells in volume proceeds in about the same way till they reach
their full size at twenty days. After that we note a difference
between them. While the outer hair cells maintain a nearly
constant volume, the volume of the inner hair cells diminishes
TABLE 77 Condensed
Ratios of the diameters of the nuclei of the outer hair cells according to the turns of
the cochlea
RATIOS BETWEEN TURNS
AVERAGE AGE
AVERAGE BODY
WEIGHT
I-II
I-II I
I-IV
days
grams
1
5
1 1.1
1 1.0
1 1.0
11
14
1.0
1.1
1.1
213
138
1.0
1.1
1.1
TABLE 78 Condensed
Comparison of the volumes of ike inner and the outer hair cells
AVERAGE VOLUMES HAIR CELLS
AVERAGE AGE
AVERAGE BODY
RATIOS OF INNER
WEIGHT
TO OUTER
Inner
Outer
days
grams
M
A
1
5
925
533
1 0.6
11
14
1665
1169
0.7
213
138
1693
1385
0.8
somewhat with age. When we consider the volume according
to the three age groups, it increases in both groups throughout
life (table 78). There are, however, large differences in the rate
of increase. The inner hair cell increases its volume at 11 days
by 80 per cent and between 11 and 213 days by less than 2 per cent.
For the outer hair cells the increase by 11 days is 120 per cent
and from 11 to 213 days, 19 per cent. At the same time the inner
are always larger than the outer hair cells, as the ratios in table
78 show.
106
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
The diameters of the nuclei in both the inner and outer hair
cells diminish in value after nine days of age. This decrease
is larger in the outer than in the inner cells. In table 79 are
given the values for the diameters of the nuclei in both inner and
outer hah* cells. In the last column are the ratios between them.
Thus, while the volumes of the outer hair cells, as compared
with the inner hair cells, become relatively larger with age (table
78), the diameters of their nuclei become relatively smaller
(table 79).
TABLE 79 Condensed
Comparison of the diameters of the nuclei of the inner and outer hair cells
AVERAGE DIAMETERS OF THE
AVERAGE
NUCLEI OF THE HAIR CELLS
RATIOS OF THE AVERAGE
DIAMETERS OF THE NUCLEI OP
AVERAGE AGE
BODY
WEIGHT
Inner
Outer
CELLS
days
grams
M
M
1
5
8.1
7.7
1 1.0
11
14
8.0
7.3
0.9
213
138
7.1
6.1
0.9
Comparison of the growth of the inner and outer hair cells
according to sex. A careful and elaborate comparison has been
made to determine whether there are differences in the growth
of the hair cells according to sex.
In table 80 are given the average values for the volumes of
the cell bodies and their respective nuclei. No significant differ-
ences according to sex were found.
Comparison of the growth of the inner and outer hair cells
according to side. The same treatment of the data was followed
as in the determination for the influence of sex. In table 81 are
given the average values for the volumes of the inner and outer
hair cells and their respective nuclei. Again no significant
differences according to side were found.
On the nucleus-plasma ratios of the inner and outer hair cells.
For the inner and outer hair cells here measured the weighted
volumes of the cell bodies and of their nuclei are entered in the
condensed table 82, and the ratios of the volume of the nucleus
GROWTH OF THE INNER EAR OF ALBINO RAT
107
to that of the cytoplasm (=cell volume less nucleus volume)
are given in the last column. This ratio increases with age,
as table 82 shows. While the ratio is 1.5 in the youngest and
smallest group, it is 9.9 in the largest. This means that as a
group these cells are continually growing in volume. This result
may be analysed for the two groups of cells involved.
TABLE 80
Average volumes of inner and outer hair cells and of their respective nuclei
in n 3 according to sex
INNER HAIR CELLS
OUTER HAIH CELLS
WEIGHTED AVERAGE
Att
BODY
NO. OF
BEX
Average volume
Average volume
VOLUME
BATS
Cell
Nucleus
Cell
Nucleus
CELLS
NUCLEI
da j/5
grams
3
7
1
0*
1213
310
815
268
915
278
8
1
9
1319
310
888
322
996
319
6
11
2
tf
1426
289
955
278
1073
281
10
2
9
1372
310
979
268
1077
278
9
10
2
cT
1701
310
1351
258
1439
271
9
2
9
1895
345
1203
278
1376
295
12
14
2
c? 1
1830
258
1344
157
1466
182
12
2
9
1886
221
1221
151
1387
168
100
146
1
cT
1687
180
1342
113
1428
129
103
1
9
1779
212
1319
108
1434
184
150
189
1
rf 1
1679
165
1382
119
1456
131
154
1
9
1639
212
1611
119
1618
142
365
205
1
tf
1739
258
1389
119
1477
154
170
1
9
1659
221
1486
113
1529
140
Volume greater in male 3
2
3
4
5
3
Volume greater in female 4
4
4
2
2
4
Equal
1
1
.
The nucleus-plasma ratio of the inner and outer hair cells
considered separately. This is shown for the inner hair cells
in table 83. The ratios are also progressive, but somewhat
larger for the earlier age groups and smaller for the oldest, than
in the previous instance.
The ratios for the outer hair cells are also progressive, and
the range is greater than for the inner hair cells as table 84 shows.
Here the ratio is 1.2 for the youngest group and 10.6 for the
108
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
oldest. This indicates that at one day and eleven days the
relative volume is less in the outer than in the inner hair cells,
but at the later age the outer hairs cells grow more.
TABLE 81
Volumes of the inner and outer hair cells and of their respective nuclei according
to side in ft 3
AGE
BODY
WEIGHT
NO. OF
BATS
SIDE
INNER HAIR CELLS
OXJTER HAIR CELLS
WEIGHTED AVERAGE
VOLUME
Average volume
Average volume
Cell
Nucleus
Cell
Nucleus
CELLS
NUCLEI
1
5
2
R.
895
299
555
248
640
261
L.
955
268
511
230
622
239
3
7
1
R.
1213
310
815
268
915
278
L.
1395
299
920
299
1039
299
6
11
2
R.
1381
322
1010
278
1103
289
L.
1416
289
923
258
1046
268
9
9
2
R.
1782
310
1177
268
1328
278
L.
1815
333
1378
268
1487
284
12
12
1
R.
1887
212
1310
151
1454
166
L.
1885
221
1132
151
1320
168
15
13
1
R.
1895
230
1522
144
1615
165
L.
1848
239
1419
151
1526
172
20
29
2
R.
1914
212
1365
144
1502
161
L.
1862
221
1472
165
1570
179
25
36
2
R.
1758
204
1307
131
1420
149
L.
1792
195
1351
131
1461
147
50
59
2
R.
1741
204
1443
125
1518
145
L.
1687
204
1305
137
1401
154
100
102
2
R.
1675
187
1355
113
1440
131
123
2
L.
1658
172
1339
113
1419
128
150
189
1
R.
1565
172
1420
113
1456
128
L.
1679
165
1382
119
1456
131
257
137
2
R.
1685
187
1377
125
1454
140
L.
1607
180
1416
119
1464
134
367
175
2
R.
1634
195
1436
113
1486
134
365
188
2
L.
1848
230
1374
113
1493
142
546
255
2
R.
1831
157
1474
119
1563
128
L.
1559
151
1353
119
1405
127
Volume greater on right side 7
8
9
3
7
6
Volumfe greater on left side 7
5
5
5
6
8
Equal
1
6
1
GROWTH OF THE INNER EAR OF ALBINO RAT
109
This seems to be important and to illustrate the fact that in
the papilla spiralis the growth of the elements lying nearer the
axis occurs earlier than that of the elements nearer the periphery.
TABLE 82 Condensed
Nucleus-plasma ratios of the inner and outer hair cells M*
AVERAGE
AGE
AVERAGE
BODY
WEIGHT
AVERAGE VOLUME OF
INNER AND OUTER HAIR CELLS
VOLUME OK
CYTOPLASM
NUCLEUS-
FLA8MA RATIOS
Cell
Nucleus
days
1
11
213
grams
5
14
138
631
1293
1462
248
226
134
383
1067
1328
1 : 1.5
:4.7-
:9.9
TABLE 83 Condensed
Nucleus-plasma ratios of the inner hair cells /**
AVERAGE
AGE
AVERAGE
BODY
WEIGHT
AVERAGE VOLUME OF 1XXER
HAIR CELLS
VOLUME
or
CYTOPLASM
NUCLEUS-
PLASMA RATIOS
Cell
Nucleus
days
1
11
213
0ms.
5
14
138
925
1665
1693
278
268
187
647
1397
1506
1 2.3
5.2
8.1
TABLE 84 Condensed
Nude us- plasma ratios of the outer hair cells
AVERAGE
AGE
AVERAGE
BODY
WEIGHT
AVERAGE VOLUME OF OUTER
HAIR CELLS
VOLUME or
CYTOPLASM
NUCLEUS-
PLASMA
RATIOS
Cell
Nucleus
days
1
11
213
grams
5
14
138
533
1169
1385
239
204
119
294
965
1266
1 1.2
4.7
10.6
17. Deiters' cells. The Deiters' cells are most delicate ele-
ments. In the literature, so far as I know, there are no exact
observations touching the growth of these cells in the papilla
spiralis, except a few data for their length. They have an
110 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
irregular form and consist of three parts, the phalangeal process,
cell body, and foot. The phalangeal process is thin, somewhat
crooked in the adult though it runs straight at an earlier stage.
As the boundary between this process and the cell body, we
take a line running through the supporting cup ('Stutzkelch' of
Held) parallel to the plane of the basilar membrane (fig. 10).
The cell body in its upper part is wide, including here a round
nucleus. It then becomes thin and passes over to the foot.
Thus it is almost impossible to get the true volume of the cells.
Therefore, we have determined the volume of the cell body
only, excluding that of the phalangeal process.
We think of the cell body as a cylinder having an average
diameter, which is calculated from four diameters measured at
four levels. The first level is just below the upper boundary
of the cell body, the second in the widest part, the third below at
about the middle of the cell body, and the last is at the narrowest
part near the foot. .
The height of the cylinder is the length of the cell body within
the limits just noted. Thus the volume obtained approximates
the value for the natural size of the cell body without the process.
In table 85 (chart 38) are given the values for the volumes of
the Deiters' cells thus computed and the diameters and volumes
of the nuclei according to age. As there are in the radial section
three rows of cells, the values given are, of course, the average
of these. At the bottom of the last column appear the ratios at
1 to 12, 1 to 20, 1 to 546, and 12 to 546 days. As we see, the
volume of the cell body increases throughout life, slowly during
the first nine days, but from twelve to twenty days very rapidly,
and then less rapidly to old age.
While the ratio from one to twelve days is 1:5.4, that from
1 to 546 days is 1:29.1, or more than five times as large.
When we consider the volumes of the cells in each turn of
the cochlea, we see that it is smallest in turn I and largest in
turn IV, though there are some exceptions before nine days
of age. Table 86 shows these relations.
The diameters of the nuclei of the cells grow, after some
fluctuations in the values at earlier stages, very slowly to old
GROWTH OF THE INNER EAR OF ALBINO RAT 111
age, as indicated in table 85 and chart 38. The ratios at the
bottom of the corresponding column show these relations. The
values for the volumes of the nuclei of the cells are given in the
last column. Here, also, the diameters in the upper turns tend to
be larger than in the basal turn. In table 87 are given the ratios
of the diameters of turn I to the three other turns. We see in
all the turns about the same ratios, 1:1.0.
In the literature we find but two observations on the diameters
of the nuclei of the Dieters' cells. Kolmer ('07) reports hi the
pig 5 [i, and von Ebner ( '02) gives in man 7 (x for the diameter
of the round nucleus of the cells.
In the rat, therefore, the diameter is larger than in these
two forms, but no significance can be attached to this difference
until correction has been made for the several techniques em-
ployed. This I am unable at present to do.
On the nucleus-plasma ratio in Deiters 1 cells. In the condensed
table 88 are given the volumes of the cell bodies and of their
nuclei together with the respective nucleus-plasma ratios. This
shows that the ratio is progressive with age. While the ratio
is at birth only 0.05, that in the oldest group is 28.3. The absolute
increase is not great at earlier stages, but by eighteen days it
is marked
The rapid change in the ratio is very interesting. Before
eight days of age the cells are still immature. Some time after
eight days they develop rapidly, seeming to play some important
part in the special functions of the cochlea.
On the length of Deiters' cells. To measure the length of
Deiters' cells we divide them into two parts, the upper and the
lower, by the boundary line between the cell body and the pha-
langeal process. The sum of these two lengths makes the total
length of the cells.
In table 89 are given the values for the total length and for
each part separately (chart 39). As in the volume of the cells,
we see an astonishing change in the development of the length.
The length of the cells increases through life, at earlier stages a
little, but at twelve days it becomes nearly twice as long as at nine
days. The ratios at the bottom of the last column show the
course of growth.
TABLE 85
The volume of Deiters' cells and the mean diameters and volumes of their respective
nuclei (chart 38)
VOLUME OF THE DEITERS* CELLS
1
NUCLEI
VOLUMES
BODY
fit
Diameters
AGE
WEIGHT
Average
I
II
III
IV
Average
I
II
III
IV
diam-
Average
volume
eters
volumes
M
M
days
grams
1
5
278
232
237
256
251
7.6
7.5
7.5
8.1
7.7
239
3
8
290
309
349
352
325
7.0
7.0
6.9
7.0
7.0
180
6
11
425
395
495
364
420
7.0
6.5
6.7
6.6
6.7
165
9
10
635
461
554 423
518
6.9
7.0
7.1
7.1
7.0
180
12
13
1122
1369 1395
1569
1364
6.5
7.0
6.9
7.1
6.9
180
15
13
1466
2187 2659
3127
2359
7.0
7.2
7.2
7.3
7.2
195
20
29
3576
427115740
6171
4939
7.6
7.8
7.9
7.9
7.8
248
25
50
36
59
4088 4467 5470
4839 5970 6258
5757
6816
4695
5971
7.3
7.3
7.2
7.5
7.3
7.5
7.4
7.4
7.3
7.4
212
212
100
112
5011
6083
7137 6607
6210
6.9
7.6
7.5
7.4
7.3
212
150
183
5755 6291 7657
6750
6613
7.5
7.6
7.5
7.1
7.4
212
257
137
5776 6540 8841
8544
7425
7.4
7.8
7.9
8.0
7.8
248
366
181
6163
6908
7701
7895
7167
7.4
7.7
7.9
7.9
7.7
248
546
255
6092 6919 8028
8152
7298
7.4
7.9
8.0
7.7
7.7
248
Ratios 1 12 days
1 5.4
1 0.9
1 20 "
19.7
1.0
1546 "
29.1
1.0
12546 "
5.4
!
1.1
TABLE 86 Condensed
Ratios of volumes of the Deiter's cells according to turns of the cochlea
RATIOS BETWEEN TURNS
AVERAGE AGE
AVERAGE BODY
WEIGHT
I-II
i-m
I-IV
days
grams
1
5
1 :0.8
1 :0.9
1 :0.9
8
11
:1.0
: 1.1
: 1.1
18
21
: 1.3
: 1.7
: 1.8
213
138
: 1.1
: 1.4
: 1.3
TABLE 87 Condensed
Ratios of the diameters of the nuclei of Deilers' cells according to turns of the cochlea
RATIOS BETWEEN TURNS
AVERAGE AGE
AVERAGE BODY
WEIGHT
I-II
I-III
I-IV
days
grams
1
5
1 1.0
1 1.0
1 : 1.1
8
11
1.0
1.0
: 1.0
18
21
1.0
1.0
:1.0
213
138
1.0
1.1
:1.0
112
GROWTH OF THE INNER EAR OF ALBINO RAT
113
90OO
8OOO
7OOO
6000
5000
4000
3OOO
2OOO
1OOO
AGE
o
25
50
50 1OO 2OO 300 4OO 5OO
Chart 38 Showing the volume of Deiters' cells and their nuclei, on the
average and according to the turns of the cochlea, table 85.
Average volume of Deiters' cells.
._. Volume of the cells in about the middle of the basal turn.
Volume of the cells in about the beginning of the middle turn.
Volume of the cells in about the middle of the middle turn.
-..-..-.. Volume of the cells in about the beginning of the apical turn.
-...-.. Average volume of nuclei of Deiters' cells, X 10.
114
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
Comparing the length of the cells according to the turn of
the cochlea, we find that after twelve days the length increases
from the base to the apex, in turn III very rapidly, in turn IV
gradually (table 90). At earlier stages the relations are irregular.
TABLE 88 Condensed
Nucleus-plasma ratios of the Deiters' cells
AVERAGE VOLUMES
VOLUME OF
NUCLEUS-
AVERAGE AGE
AVERAGE BODY
CYTOPLASM
PLASMA RATIOS
WEIGHT
Cell
Nucleus
.M
M
M
days
grams
1
5
251
239
12
1 : 0.05
8
11
657
172
485
: 2.8
18
21
3649
221
3428
: 15.5
213
138
6483
221
6262
:28.3
TABLE 89
Length of cell body and of processus phalangeus of Deiters' cells p (chart 39)
LENGTH OF THE CELL BODY
LENGTH OF THE PROCESSUS
PHALANGEUS
TOTAL
BODY
LENGTH
AGE
WEIGHT
Turns of cochlea
Turns of cochlea
OF THE
CELLS
I
II
III
IV
Average
I
II
ill
IV
Average
days
gms
1
5
8
8
8
9
8
20
19
20
15
19
27
3
8
8
9
9
10
9
16
17
18
18
17
26
6
11
9
9
11
10
10
19
22
23
22
22
32
9
10
18
12
13
11
14
18
21
26
24
22
36
12
13
31
35
40
43
37
18
22
29
25
24
61
15
13
34
37
40
43
39
21
25
32
31
27
66
20
29
39
41
49
49
45
19
23
30
34
27
72
25
36
42
43
51
51
47
17
21
30
32
25
72
50
59
41
45
53
53
48
16
22
30
34
26
74
100
112
43
45
54
53
49
17
25
29
31
26
75
150
183
45
46
53
52
49
17
22
32
34
26
75
257
137
43
46
56
58
51
18
24
28
31
25
76
366
181
43
48
55
55
50
17
23
29
32
25
75
546
255
46
49
56
56
52
16
23
30
33
26
78
Ratios 1 12 days
1 :4.6
1 :1.3
1 :2.3
1 20 "
:5.6
: 1.4
:2.7
1546 "
:6.5
:1.4
:2.9
12546 '"
: 1.4
:1.1
: 1.3
GROWTH OF THE INNER EAR OF ALBINO RAT
115
When we consider the length of the cell body, it is remarkable
that the increase takes place so rapidly. While at 1 day it
measures only 8 (x and at nine days only 14 ji, it increases very
suddenly at twelve days of age, and after that slowly but con-
tinuously (table 89).
TABLE 90
Total length of Deiters' cells according to turns of the cochlea (chart 39)
AGB
BOOT WEIGHT
TURNS OF THE COCHLEA
I
II
III
IV
days
grams
1
5
28
27
28
24
3
8
24
26
27
28
6
11
28
31
34
32
9
10
36
33
39
35
12
13
49
57
69
68
15
13
55
62
72
74
20
29
58
64
79
S3
25
36
59
64
81
83
50
59
57
67
83
87
100
112
60
70
83
84
150
183 '
62
68
85
86 -
257
137
61
70
84
89
366
181
60
71
84
87
546
255
62
72
86
89
80
M
60
40
20
n
^
<
="
>
"^
/
/
-
-
~
~
/
,'
>
P
-
;
*-.
'*
,/
"'
ft
G
E
DA
*/c
Tb
25 50 50 10O 200 30O 400
Chart 39 The length of Deiters' cells, tables 89 and 90.
500
Total length of the cells.
Length of the cell bodies.
Length of processus phalangeus.
116
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
In the ratios at the bottom of table 89 this is shown very
evidently and in each turn this relation is to be seen.
For the length of the phalangeal process the story is quite
different. It increases from birth to twelve days a little; at
fifteen days it reaches full size, and then holds its value (table 89) .
After three days the length is smallest in turn I and largest in
turn IV. This relation lasts to old age.
Comparing the growth of the length of the cell body and
phalangeal process, there is a large difference between them.
While the length in the phalangeal process is at birth over twice
that of the cell body, at 546 days it is only half that of the cell
TABLE 91
Total length of Deiters' cells in fj, (Retzius)
AGE
RABBIT
CAT
Basal
Middle
Apical
Average
Basal
Middle
Apical
Average
turn
New-born
48
70
60
59
45
65
48
53
2
45
66
54
55
1
3
45
60
7
80
90
75
82
49
69
63
60
10
98
100
114
104
11
75
90
45
70
14
84
105
112
100
30
54
75
70
66
body. Thus the increase of the total length of Deiters' cells
is due chiefly to the increase in the length of the cell body.
Retzius ('84) gives the length of Deiters' cells in the rabbit
and cat as in table 91.
Table 91 shows that in both the rabbit and the cat the length
at all ages is greater, and especially at the earlier stage is twice
as great, as in the rat. In the rabbit there is a rapid increase
in length between seven and ten days. For the cat the values
are smaller, nearer those of the rat, and show less change between
birth and thirty days.
18. Summary and discussion. Using the foregoing data on
the form and measurements of the elements of the cochlear
duct, I desire here to summarize the results and to discuss the
consequent changes in the form of the organ of Corti (table 92).
GROWTH OF THE INNER EAR OF ALBINO RAT 117
We have already noted that at birth the greater epithelial
ridge constitutes the main part of the tympanic wall, and the
lesser epithelial ridge, from which arises later the most important
organ, is represented by a small and undeveloped prominence.
With age this greater ridge disappears gradually and is trans-
formed into a furrow lined with low epithelial cells, the sulcus
spiralis internus (Waldeyer). These changes appear first at the
base and then pass gradually to the upper turns. In the lesser
ridge also there are important developmental changes. At first
the hair cells and pillar cells grow, and just before the special
function appears, striking changes are seen in Deiters' and
Hensen's cells. These increase, especially in their length, very
rapidly.
Thus the papilla spiralis, which hitherto had its highest
point at the summit of the arch of Corti, shows a remarkable
change of form, as the outer part of the papilla increases its
height, so that finally Hensen's cells mark the highest point
in the papilla. The surface then ceases to be parallel to the
basilar membrane, and slopes inward, making with the basilar
membrane an acute angle opening outward. At the same time
the papilla spiralis appears to be shifted inward i.e., towards
the axis.
Kolliker has described how the cells, from which the pillars or
rods of Corti arise, at first stand nearly parallel, but later separate
at their base. He thought that this "von einem Langen-
wachstum (?) der Zellen selbst oder ihrer Grundlage, der Mem-
brana basilaris, abhiingen kann. "
Hensen ('63) first studied this interesting problem in the ox
and found it to depend on a peculiar process. He regarded the
inward migration as taking place chiefly in the inner pillar cell.
The outer pillar cell in the upper turn moves somewhat outward ;
in the base, however, inward. Moreover, the outer pillar cell
increases its length during the development of the papilla much
more than the inner does. Thus the summit of the arch of Corti
and therefore the papilla spiralis shifts inward on the basilar
membrane.
118
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
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habenula perforata
Breadth of membran!
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jj
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GROWTH OF THE INNER EAR OF ALBINO RAT
119
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120
Bottcher ( '69. 72) disagreed with Hensen, though he has con-
firmed, as did Middendorp ('67), the striking inward spreading
of the base of the inner pillar cell.
Gottstein] ( 72) held that the inner pillar cell does not move
inward, but that the increase in the length of the labium tym-
panicum may explain the peculiar approach of the habenula
perforata to the arch of Corti.
Retzius ('84) agreed in general with Hensen 's assertion that
in the course of development the surface of the sense organ
comes to lie under the basal surface of the membrana tectoria.
He thought that this change of position is brought about "weni-
ger in dem Verhalten der Pfeilerzellen, sondern vor allem in
dem starken Wachstum der Deitersschen Zellen und der von
aussen andriickenden Hensenschen Stiitzzellen, ' and that,
further, "vielleicht die Membrana tectoria selbst durch eigenes
Wachstum und durch Vergrosserung des Limbus mit seinem
Vorspriingen" contributes to this.
Held ('09) agrees with Hensen on the whole.
Prentiss ('13, p. 450) denies the wandering of the spiral organ
as follows: ''There is no necessity for, and my preparations
afford no proof of, an inward shifting of the spiral organ and
a consequent displacement of the membrana tectoria "
Hardesty ('15, pp. 60 and 61) discussed the relative position
of the spiral organ with reference to the basal surface of the
tectorial membrane and says " the developed spiral organ acquires
its position well under the basal surface of the tectorial membrane
almost entirely by being carried axisward during the completion
of the membrane." "In the apical turn, where these changes
are greatest, the hair cells of the organ may be carried axisward
a distance nearly half the width of the membrane. The upgrowth
of the outer supporting cells also forces axisward the apical
ends of the elements of the spiral organ and in this way con-
tributes a small part to the shift in the relative position of the
hair cells. A slight increase in width of the vestibular lip of
the spiral limbus may contribute a still smaller part by extending
the membrane outward."
GROWTH OF THE INNER EAR OF ALBINO RAT 121
I obtained from the measurements given in the tables the
following results concerning the position of the papilla spiralis
under the basal surface of the tectorial membrane.
As already stated, since the habenula perforata may be con-
sidered after birth as a punctum fixum (Hensen), it is found
that the inner pillar cell shifts inward at its inner basal corner
during the earlier stage of life. At six days of age it almost
always reaches the habenula perforata in the basal turn, though
not yet in the apical. At nine days there is no distance between
the- habenula perforata and the inner corner of the inner pillar
cell.
Gottstein's assumption (no measurements) that the labium
tympanicum grows outward and approaches to the arch of Corti
is not applicable to the rat, as shown by my tables.
The outer pillar cell also moves outward in all the turns
through life, but only slightly after nine days. This result does
not agree with that of Hensen ('63), who found in the ox the
outer pillar cell to move inward a little at the base, not at all
in the middle turn and outward at the apex. Bottcher 's outward
movement of the outer pillar cell at the hamulus in the cat is
90 y. and much larger than in the rat.
Contrary to Hensen, Retzius ('84) also finds in the rabbit an
outward movement of the base of the outer pillar cell throughout
all the turns. On the other hand, during the earlier stages of
development, the top of the arch of Corti moves outward from
the labium vestibulare through the outward pressure of the
greater epithelial ridge. At this stage the main part of the
membrana tectoria does not yet reach to the sense cells, though
the part produced from the lesser epithelial ridge spans the
spiral organ and connects with the outer part of the papilla.
After nine days of age the condition of the organ is quite
different. The most remarkable anatomical changes from the
earlier condition are the rapid increase in the length of the outer
pillar cells, in the height of the pillar cells above the basilar
membrane, in the height of the papilla spiralis at the third series
of the outer hair cells, in the height of Deiters' cells, and in the
height of Hensen 's supporting cells. Also the tunnel of Corti
appears.
122 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
The greater epithelial ridge has already disappeared in large
part and been replaced by a furrow. Pressure displacement
of tissue in the direction of the least resistance is common in
organogenesis. Thus the inner pillar cell is subject to pressure
by the rapid growth of the outward lying and greater part of
the papilla spiralis and moves in the direction of the least resis-
tance, therefore inward; the head most and the base not at all.
As shown in table 44, the rapid decrease in the radial distance
between the labium vestibulare and the head of the inner pillar
cell is very evident. The arch of Corti changes its form, now
inclining inward, instead of outward as heretofore. The lamina
reticularis runs not parallel to the basilar membrane, but ascends
outward. The tunnel of Corti also changes more or less its form.
Nuel 's space now appears possibly as a result of this displacement
of the papilla spiralis. Thus we see a change in the position
of the sense organ with reference to the membrana tectoria.
With the inward shifting of the papilla, the hair cells come
under the basal surface of the membrana tectoria. It is probable
that the increase of the relative length of the membrane also
takes part in this, since the increase in the breadth of the inner
zone of the membrana tectoria from one to twelve days is as
1:3.4 (table 4), while the increase in the breadth of the basilar
membrane is as 1:0.5 during the same interval (table 7).
Prentiss' ('13) statement that an inward shifting of the papilla
spiralis and a consequent displacement of the membrana tectoria
does not take place (in the pig) is not applicable to the rat.
In the rat the labium vestibulare and the inner edge of the
head of the inner pillar cell are also two definite points in the
same sense, and using them we see an inward shifting of the
organ of Corti. I imagine that his observation may have misled
him, since the tectorial membrane arises in his preparations
from both greater and lesser epithelial ridges, and from the
earlier stages covers with its outer part the papilla spiralis.
Thus the shifting of the organ inward does not necessitate a
change in the position of the papilla with reference to the mem-
brane. In his study of the tectorial membrane in the same
animal (pig) , Hardesty ( ' 13) describes a large displacement of the
papilla spiralis inward.
GROWTH OF THE INNER EAR OF ALBINO RAT 123
According to him, the shifting of the organ consists of, 1, the
moving axisward of the organ itself, and this constitutes the
main shift; 2, the upgrowth of the outer supporting cells, and
this contributes a small part to the shift, and, 3, a slight increase
of the vestibular lip of the spiral limbus which may contribute
a still smaller part. The relation in the rat, however, is different.
The moving inward of the papilla itself is not seen in the rat.
In the earlier stages the inner basal corner of the inner pillar
cell alone shifts inward and reaches the habenula perforata.
On the other hand, the outer pillar cell moves outward and
the head of the inner pillar cell also, at earlier stages, towards
the cells of Hensen. Therefore, during the earlier stages the
arch of Corti moves rather outward, owing to the pressure of
the growth of the greater epithelial ridge. Since the habenula
perforata is to be regarded as a fixed point, the inward displace-
ment of the head of the arch of Corti and of the papilla spiralis
is not due to the active shifting inward of the organ itself, as
Hardesty ('15) thinks, but to the disappearance of the greater
ridge and the passive pressure exerted by the upgrowth of the
outer pillar cells and Deiters' and Hensen 's cells. The vestibular
lip of the spiral lamina and the tectorial membrane itself both
increase in their length a little, and these increases play some
part in the change of the position of the papilla spiralis with
reference to the basal surface of the tectorial membrane.
The membrana basilaris is not concerned with the moving
inward of the organ. It increases its length with age in all the
turns, but we do not find the change in the position of the feet
of the pillar cells on the membrane in such a sense that the
feet move inward on it.
Thus the shifting of the papilla spiralis inward in the rat
during the development takes place rather in the manner de-
scribed by Retzius.
Hardesty ('15) states that in the apical turn of the cochlea the
organ may be moved axisward a distance equal to about half
the maximum width of the greater epithelial ridge, the maximum
width of the ridge representing approximately the width of the
outspanning zone of the membrane produced upon it.
124
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
No other author reports such a high degree of the inward
shifting of the organ. I have not studied the pig, but in the
rat I get the average distance between the labium vestibulare
and the inner edge of the head of the inner pillar cell as follows
(table 93).
TABLE 93
Average distance between the labium vestibulare and the inner edge of the inner
pillar cell in n (albino rat)
AGE
BODY WEIGHT
TURNS OF COCHLEA
I
II
III
IV
Average
days
grams
(1) 5
(2) 154
Difference betw
1 and 2
9
102
een age groups
94
63
31
124
100
24
1,54
134
20
165
148
17
23
Therefore, in the rat the organ moves inward on the average
of 23 [A; that is, in the ratio of 1:0.16 of the maximum distance
between these two points. It may be noted that the difference
in this table is not the same in the several turns, but diminishes
from base to apex a relation which is the reverse of that reported
by Hardesty ('15) in the pig. I have no explanation for these
differences except their possible dependence on the different
animals used.
C. On the growth of the largest nerve cells in the ganglion spirale.
Observations. For the present studies the fourteen age groups
used in the previous observations on the growth of the tympanic
wall of the cochlear duct were employed. In order to see the
relation between the growth of the papilla spiralis and the cells
of the ganglion spirale, both studies were made on the same
sections. In addition, however, I made cross-sections of the
cochlea (i.e., at right angles to the axis) in several age groups
to follow the growth and the changes in the form of the nerve
cells as they appear in this plane. The data for the animals
thus used are given in table 94.
GROWTH OF THE INNER EAR OF ALBINO RAT
125
For the measurement of the nerve cells a Zeiss system was used
with a micrometer eyepiece, having each division equal to 2jx.
Since we have in the radial vertical section of the cochlea of the
rat at least four turns, there are four cell groups available in
each section (fig. 3). The ten largest cells in each ganglion
were measured, and thus a total of forty cells in a section were
taken for the measurement of the nucleus and the cell.
We used, as stated, four cochleas in each age group, so that
160 cells were measured for each age. Also in the cross-sections
the four nearly corresponding turns were used for the measure-
ments, selecting the ten largest cells in each turn.
TABLE 04
Data on rals used for cross-sections of the cochlea ganglion spirale
AGE
BOOT WEIGHT
BODY LENGTH
BEX
8IDE
HEARING
days
grams
15
20
84
(?
L.
Prompt response
20
27
93
d"
L.
25
39
114
P
L.
100
95
152
<?
R.
150
169
192
9
L.
371
220
206
c?
L.
In the measurement of the cell bodies the two maximum
diameters at right angles to each other were determined, and
also the two corresponding diameters for the nuclei.
Here it is to be noted that the expressions turn I, II, III,
and IV are used in the same sense as in the earlier chapters.
In table 95 (chart 40) are given the values for the average
diameters of the cell bodies and their nuclei in the ganglion
spirale in the radial vertical section according to fourteen age
groups. Under 'cell body, diameter,' the first column gives the
long, the second the short, and the third the computed diameter;
i.e., the square root of their products. These last values ap-
proximate the mean diameters of the nerve cells. At the foot
of the third column are given the ratios from 1 to 20, 1 to 546,
and 20 to 546 days. The values for the diameters of the nurlei
are similarly given and also the ratios.
126
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
As the tables and charts show, the diameters of the cell bodies
and also of their nuclei are largest at twenty days of age. After
that age they diminish, gradually. While the ratio for one to
twenty days is 1:1.7 in the cell bodies and 1:1.3 in the nuclei,
that for 1 to 546 days is 1:1.6 and 1:1.2, respectively.
TABLE 95
Diameters of the cell bodies and their nuclei in the ganglion spirale (radial-vertica I
section) (chart 40)
Diameters in M
Cell body
Nucleus
AGE
BOOT
BODY
WEIGHT
LENGTH
Long
Short
Computed
Long
Short
Computed
days
grams
mm.
1
5
48
11.0
10.0
10.5
8.2
7.6
7.9
3
8
56
12.0
11.1
11.5
8.2
7.8
8.0
6
11
63
13.6
12.3
12.9
8.8
8.1
8.4
9
10
58
14.3
12.8
13.6
8.9
8.2
8.5
12
13
70
14.6
13.1
13.8
8.7
8.2
8.5
15
13
75
15.7
14.1
14.9
9.1
8.4
8.7
20
29
95
19.0
17.3
18.1
10.3
10.0
10.2
25
36
104
18.5
16.9
17.7
10.2
9.9
10.1
50
59
125
18.5
16.6
17.5
10.3
9.7
10.0
100
112
159
18.1
15.7
16.9
9.8
9.2
9.5
150
183
190
18.2
15.3
16.7
9.6
8.8
9.2
257
137
175
18.5
15.3
16.8
9.9
9.4
9.6
366
181
191
18.6
15.3
16.9
9.8
9.0
9.4
546
255
213
18.6
15.3
16.9
9.7
9.0
9.4
Ratios
120 days
1:1.7
1:1.3
1546 "
:1.6
:1.2
20546 "
:0.9
:0.9
In table 96 (chart 41) are a series of computed diameters
of the cell bodies and of their nuclei according to the turns of the
cochlea. At the bottom of each column are given the ratios
from 1 to 20, 1 to 546, and 20 to 546 days. Determining the
ratios for each column, it appears that in general the diameters
of the cell bodies and their nuclei are largest at twenty days
throughout all the turns. This increase is very considerable from
fifteen to twenty days. Then they decrease very slowly till
546 days.
GROWTH OF THE INNER EAR OF ALBINO RAT
127
Table 97 enables us to compare the ratios in the diameters of
the cell bodies and their nuclei in turns I, II, III, and IV in the
condensed age groups. In both the cell bodies and their nuclei
the ratios become slightly larger in passing from the basal toward
the apical turn, except in the one day group, which it reversed.
On the comparison of the diameters of the nerve cell bodies
and their nuclei in the ganglion spirale according to sex. For
this comparison seven age groups were used. In each age group
we have sometimes one, sometimes two cochleas of the same sex.
*u
M
15
10
5
r\
/
'*
**
-4
>
1
'<
1
j
f *
*
/
^
?
""
-i
_
_
___
J]
_
-.
. _,
-
_
..
_
_.
v*
'
*
G
E
D
A
/Si
25 50 5Q .Qo 2(X) 30Q 40Q
5OO
Chart 40 Showing the computed diameter of the largest cell bodies and their
nuclei from the ganglion spirale, table 95.
----- Diameters of the cell bodies.
---------- Diameters of the nuclei.
In the latter case the average value is recorded. In table 98
are given the values for these diameters, and it is plain that
there is no significant difference in these values according to sex.
On the comparison of the diameters of the nerve cell bodies
and their nuclei in the ganglion spirale according to side. For
this purpose fourteen age groups were employed. In most
cases two cochleas from the same side were used in each age group.
In these cases the average value is recorded. Table 99 shows the
values for the diameters of the cell bodies and their nuclei accord-
ing to side, but reveals no evident difference in this character.
128
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
On the morphological changes in the ganglion cells during
growth. As my sections could not be stained with thionine, my
observations on the Nissl bodies are incomplete, yet the slides
stained with Heidenhain's iron haematoxylin and van Gieson's
stain, as well as by haematoxylin and eosin, were helpful here.
TABLE 96
Computed diameters of the cell bodies and their nuclei in the ganglion spirale
according to the turns of the cochlea (chart 41 )
AGE
days
BODY
WEIGHT
gms
TURNS OF THE COCHLEA
Computed diameters M
I
II
in
IV
Cell
body
Nucleus
Cell
body
Nucleus
Cell
body
Nucleus
Cell
body
Nucleus
1
5
11.0
8.0
10.8
8.2
10.4
8.0
9.6
7.4
3
8
11.5
7.9
11.5
7.9
11.7
8.0
11.3
8.1
6
11
12.9
8.4
12.6
8.2
13.0
8.5
13.3
8.6
9
10
13.4
8.4
13.4
8.5
13.6
8.6
13.7
8.6
12
13
13.6
8.1
13.5
8.1
13.8
8.6
14.7
9.0
15
13
14.8
8.6
15.0
8.6
14.6
8.6
15.0
9.2
20
29
17.6
10.0
17.6
9.9
18.1
10.2
19.0
10.4
25
36
16.9
9.9
17.6
10.0
17.6
10.1
18.4
10.3
50
59
17.2
9.7
17.2
9.7
17.6
10.0
17.9
10.1
100
112
16.9
9.6
16.9
9.4
16.3
9.3
16.9
9.6
150
183
16.9
9.3
16.3
9.0
16.6
9.1
17.0
9.1
257
137
16.7
9.6
16.7
9.4
16.9
9.7
17.0
9.7
366
181
16.7
9.3
16.4
9.2
16.7
9.1
17.7
9.7
546 255
Ratios 1 20 day*
1546 "
20546 "
15.8
1:1 .6
9.2
1:1.3
16.3
1:1.6
9.4
1:12
16.9
1:1.7
9.4
1:1.3
17.4
1:2 .0
9.5
1:14
1 5
1 2
1 5
: 1 2
1 7
1 2
1 8
: 1 3
:1.0
:0.9
:0.r-
: 1.0
:0.?'
:0.9
:O.S
: 0.9
TABLE 07 Condensed
Ratios of the diameters of the cells and nuclei of the ganglion spirale
AVERAGE
AGE
AVERAGE
BODY
WEIGHT
RATIOS BETWEEN TURNS
I-II
l-lll
I-IV
Cell body
Nucleus
Cell body
Nucleus
Cell body
Nucleus
days
1
8
18
13
grams
5
11
21
138
1 :0.98
:0.99
: 1.01
:0.99
1: 1.25
: 1.00
: 1.00
:0 99
1:0-95
: 1.01
: 1.01
: i.OI
1 : 1 . 00
: 1.02
: 1.01
: 1 . 00
1 : . 87
: 1.03
1.04
: 1.04
1 :0.93
: 1.05
: 1 . 05
: 1.02
GROWTH OF THE INNER EAR OF ALBINO RAT
129
19
M
18
17
16
15
14
13
12
10
9
Si;
DAYSi-
i i
25
50
, oo 2OO 3OO 4OO
Chart 41 'The computed diameter of the largest cell bodies and of their
nuclei from the ganglion spirale, according to the turns of the cochlea, table 96.
Upper graphs: diameters of the coll bodies. Lower graphs: diameters of the
nuclei of the cells.
130
Figure 13 illustrates semidiagrammatically the nerve cells
in the spiral ganglion of the albino rat at 1 day and at 20 and 366
days.
The body of the ganglion cells at birth is small and has the
characteristic fetal form. The cytoplasm is homogeneous and
scanty and the Nissl bodies are not yet seen. The nucleus forms
TABLE 98
Comparison according to sex of the diameters of the cell bodies and the nuclei in
the ganglion spirale
AGE
BODY WEIGHT
NO. OF RAT8
SEX
COMPUTED DIAMETERS M
Cell
Nucleus
days
grams
3
7
1
&
11.4
8.0
8
1
9
11.4
8.0
6
11
2
tf
13.1
8.5
10
2
9
12.8
8.4
9
10
2
c?
13.6
8.5
9
2
9
13.5
8.6
12
14
2
c? 1
13.7
8.5
12
2 .
9
13.9
8.4
100
146
. 1
<?
17.2
9.6
103
1
9
16.9
9.4
150
189
1
d 1
16.5
9.1
154
1
9
17.1
9.1
365
205
1
d 1
16.3
9.0
170
1
9
16.7
9.1
Average male
14.5
8.7
Average f e male
14.6
8.7
Male larger than female
3
3
Female larger than male
3
2
Male and female equal
1
2
the greater part of the cell. The chroma tin is not yet well
differentiated, and the so-called 'Kernfaden' are not visible.
The sharply marked nucleolus is in most cases in the central
position, but sometimes located peripherally.
The cytoplasm matures rapidly. At six days the Nissl bodies
appear, though they are of course, less abundant and smaller
than in the later stages. The nucleus develops also and the
chromatin is well differentiated. Thus the development in both
the cell body and the nucleus proceeds rapidly in the earlier
stage.
20 Days
13
366 Days
Fig. 13 Showing semi-diagrammatically the size and the morphological
changes in the ganglion cells in the ganglion spirale of the albino rat at the age of
1, 20 and 366 days. All cell figures have been uniformly magnified 1000 diameters.
GROWTH OF THE INNER EAR OF ALBINO RAT
131
At twenty days the cell body reaches its maximum size. The
Nissl bodies are large and abundant. The nucleus also attains
TABLE 99
Comparison according to side of the cell bodies and their nuclei in the ganglion
spirale
AGE
SIDE
COMPUTED I.I \ M K r Ml- ft
Cell
Nucleus
days
grams
1
5
2
R.
10.6
8.0
L.
10.4
7.8
3
7
1
R.
11.4
8.0
L.
11.5
8.0
6
11
2
R.
13.0
8.5
L.
12.9
8.4
9
9
2
R.
13.4
8.5
L.
13.7
8.6
12
12
1
R.
13.9
8.4
L.
14.0
8.4
15
13
1
R.
14.7
8.6
L.
14.8
8.5
20
29
2
R.
18.0
10 1
L.
18.5
10.2
25
36
2
R.
17.6
10.1
L.
17.7
10 1
50
59
2
R.
17.5
9.9
L.
17.5
9.8
100
102
2
R.
16.8
9.5
123
L.
17.0
9.5
150
189
1
R.
16.4
9.2
L.
16.5
9.1
257
137
2
R.
17.1
9.7
L.
16.6
9.5
367
175
2
R.
17.3
9.7
365
188
L.
16.5
9.1
546
255
2
R.
16.9
9.3
L.
16.9
9.9
Average right side
Average left side
Right larger than left
Left larger than right
Right and left equal
15.3
ir>.:j
4
8
2
9.1
'.M)
7
2
5
its maximum size at this age, though the rate of increase is slower
than that for the cell body. With this increase of size the his-
tological structure becomes that of the adult rat. Then, as the
132
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
age advances, the size of both the cell body and of the nucleus
slowly diminishes, while within the cytoplasm the differentiation
of the Nissl bodies progresses. This relation is seen in the figure
of the cell at 366 days, which shows that the absolute volume
of the cell body and also of the nucleus is smaller than at twenty
days.
From twenty to 366 days, gradual and progressive changes
in all histological structures can be seen, though there are no
sudden changes.
TABLE 100
Diameters of the cell bodies and their nuclei in the ganglion spirale in cross sections
of the cochlea (chart 4%)
DIAMETERS IN M
AGE
BODY
Cell body
Nucleus
Long
Short
Computed
Long
Short
Computed
days
grams
15
20
15.7
14.3
15.0
9.3
8.4
8.8
20
27
18.3
16.6
17.4
10.3
10.0
10.1
25
39
18.0
16.6
17.3
10.1
9.8
9.9
100
95
17.6
16.2
16.9 '
9.9
9.5
9.7
150
169
17.4
16.0
16.7
9.8
9.1
9.4
371
220
16.5
15.8
16.2
9.5
8.6
9.0
Ratios 15 25 days
1 1.1
1 1.1
15371 "
1.1
1.0
25371 "
1.0
0.9
The question here arose whether this change in volume was
in any way related to a shift in the long axis of the cell at the
later ages. To answer this difficult question it was deemed
desirable to compare the form of the ganglion cells obtained in
the cross-section with that found in the radial section of the
cochlea. In table 100 (chart 42) are given the values for the
diameters of the cell bodies and their nuclei in the ganglion
spirale in the cross-section. Below are given the respective
ratios from 15 to 25, 15 to 371, and 25 to 371 days. Both cell
body and nucleus increase in size up to twenty days and then
diminish very slowly, as the age advances. These are similar
to the relations found in the radial sections.
GROWTH OF THE INNER EAR OF ALBINO RAT
133
Looking at the diameters of the cell bodies and their nuclei
in each turn (table 101), we do not find in the later age groups a
regular increase in passing from the base toward the apex, as
in the cells on the radial section. The differences are generally
TABLE 101
Diameter of the cell bodies and their nucki in the ganglion spirale according to the
turns of the cochlea (cross section)
TURNS OV THE COCHLEA
AGE
BODT
WEIGHT
I
II
ill
IV
Computed diameters ft
Cell
body
Nucleus
Cell
body
Nucleus
Cell
body
Nucleus
Cell
body
Nucleus
days
15
grams
20
15.0
8.7
14.7
8.8
14.9
8.9
14.9
9
20
27
16.7
9.7
17.2
10.0
17.5
10.1
18.1
10 6
25
100
39
95
16.9
17.2
10.0
10.0
17.2
16.9
9.9
9.6
17.6
16.7
9.8
9.6
17.3
16.8
10.0
9 6
150
169
17.0
9.9
16.6
9.3
16.6
9.4
16.4
9 1
371
Ratio 15-
220
371 days
16.2
1:1.1
9.6
1:1.1
16.2
1:1.1
9.1
1:1.0
16.0
1:1.1
8.7
1:1.0
16.3
1:1.1
9.0
1:1.0
20
15
10
AGE DAYS-
O
25
50
Chart 42 The average diameter of the largest cell bodies and of their
nuclei of the nerve cells from the ganglion spirale, after 15 davs (cross-section)
table 100.
Cell bodies. -.-.-.-.-. Nuclei.
134 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
far smaller than on the radial section. This result seems to have
some connection with the position of the long axis of the ganglion
cells in relation to the axis of the cochlea.
Comparing the diameters of the cell bodies and their nuclei
in nearly corresponding places in the radial and cross-section,
the long diameters of the cells are in each age group almost
always larger in the radial than on the cross-section. Therefore
the cells are somewhat ovoid. The short diameters, however,
are at the same age sometimes longer, sometimes shorter on the
radial than on the cross-sect on. This is probably due to the
fact that in the upper turns the cells stand with their long diameter
more nearly parallel to the axis of the modiolus, and therefore,
on passing from the upper to the lower turn, the long axes of
the cells become more inclined to the modiolus.
In order to show that the cell form is ovoid, I reconstructed
the cells at 15, 100, and 365 days of age by the usual method,
and obtained models which agreed in form with that determined
by the microscope.
It appears, therefore, that while there is some difference in
the diameters of these cells according to the plane of the section,
neverthless, the change in volume after twenty days is similar
in both cases, and so this change does not depend on the plane in
which the sections were made.
On the nucleus-plasma relations of the cells in the ganglion
spirale. The computed diameters of the cell bodies and their
nuclei, measured on radial sections, are given in table 102 and
the nucleus-plasma ratios have been entered in the last column.
The ratio is at one day only 1:1.3 and increases rapidly and
regularly till twenty days; after that period there are slight fluc-
tuations. Generally speaking, the ratios increase with the ad-
vancing age of the rat, but after twenty days only very slightly.
Thus we see that the nucleus-plasma relation nearly reaches an
equilibrium at twenty days, though the cells mature slowly
even after that time.
When we consider this relation according to the turns of the
cochlea, we find that this ratio increases in all the turns regularly
and definitely till twenty days, after which there are some
GROWTH OF THE INNER EAR OF ALBINO RAT
fluctuations (table 103). Thus we see here also the same relation
as before.
TABLE 102
Nucleus-plasma ratios of cells in the ganglion spirale (radial-vertical section)
AGE
BODY
WEIOHT
BOOT
LENGTH
COMPUTED DIAMETERS M
Cell body
Nucleus
N ucleus-plasma
ratios
days
grams
mm.
1
5
48
10.5
7.9
1 : 1.3
3
8
56
11.5
8.0
:2.0
6
11
63
12.9
8.4
:2.6
9
10
58
13.6
8.5
:3.1
12
13
60
13.8
8.5
:3.3
15
13
75
14.9
8.7
:4.0
20
29
95
18.1
10.2
:4.6
25
36
104
17.7
10.1
:4.4
50
59
125
17.5
10.0
:4.4
100
112
159
16.9
9.5
:4.6
150
183
190
16.7
9.2
:5.0
257
137
175
16.8
9.6
:4.4
366
181
191
16.9
9.4
:4.8
546
255
213
16.9
9.4
:4.8
TABLE 103
Nucleus-plasma ratios of cells in the ganglion spirale according to the turns of the
cochlea. Based on table 96
AQB
BODY WEIOHT
TURNS Or THE COCHLEA
I
ii
in
IV
days
grama
1
5
1 :1.6
1 :1.5
1 :1.2
1 : 1.2
3
8
:2.1
:2.1
:2.1
:1.7
6
11
:2.6
:2.6
:2.6
:2.7
9
10
:3.1
:2.9
:3.0
:3.0
12
13
:3.7
:3.6
:3.1
:3.4
15
13
:4.1
:4.3
:3.9
:3.2
20
29
:4.5
:4.6
:4.6
:5.1
25
36
:4.0
:4.5
:4.3
:4.7
50
59
:4.6
:4.6
:4.5
:4.6
100
112
:4.5
:4.8
:4.4
:4.5
150
183
:5.0
:4.9
:5.1
:5.5
257
137
:4.3
:4.6
:4.3
:4.4
366
181
:4.8
:4.7
:5.2
:5.1
546
255
:5.1
:4.2
:4.8
:5.1
136
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
In the nucleus-plasma ratio of the cells on the cross-section,
as shown in table 104, the increase with age is very regular.
As the diameters of the cell bodies and their nuclei decrease
slowly after twenty days, this increase of the ratio means that
the nuclei are diminishing relatively more rapidly than the
cytoplasm.
Comparing these ratios from the radial and cross sections,
we find that they agree (table 105) .
TABLE 104
Nucleus-plasma ratios of the cells in the ganglion spirale (cross-sections)
COMPUTED DIAMETERS M
BODY LENGTH
AGE
BODY WEIGHT
Cell body
Nucleus
Nucleus-plasma
ratios
days
grams
mm.
15
20
84
15.0
8.8
1 4.0
20
27
93
17.4
10.1
4.1
25
39
114
17.3
9.9
4.3
100
95
152
16.9
9.7
4.5
150
169
192
16.7
9.4
4.6
371
220
206
16.2
9.0
4.8
TABLE 105
The nucleus-plasma ratios according to the plane of the section at two age periods
albino rat
AGE
NUCLEUS-PLASMA RATIO
ON THE RADIAL SECTION
NUCLEUS-PLASMA RATIO
ON THE CROSS SECTION
AGE
days
15
1 :4.0
1 :4.0
days
15
366
1 :4.8
1 :4.8
371
Discussion. According to the foregoing data, the maximum
size of the cells in the ganglion spirale, at twenty days, is in
cross-sections about 18.7 x 16.9 y. for the cell body and 10.3 x
10.0 [L for the nucleus. Both the long and short diameter of
the cell body thus obtained is therefore a little less than that
obtained in the radial section, while the diameters for the nu-
cleus are the same.
In the literature we have not found any data for the Norway
rat, but there are a few observations on the size of these cells
in other mammals by Kolliker ('67) and von Ebner ('02).
GROWTH OF THE INNER EAR OF ALBINO RAT
137
Schwalbe ('87) and Alagna ('09) find these ganglion cells 25
to 30 JJL in diameter in the guniea-pig and cat.
Alexander ('99) has also reported measurements on a series
of mammals, but as the size of such cells is greatly influenced
by the method of preparation, and as our averages are based
on the largest cells while those of other authors have been ob-
tained in a different manner, it seems best not to report the other
values in the literature, as they are sure to be misleading.
TABLE 106
Showing the changes with age in the diameters of the cells and the nticlei of the
sjriral ganglion afnd the lamina pyrmidalis of the cerebral
cortex, respectively
AGE '
CELL BODY IN
THE OANQL.
SPIRALS COMPUT-
ED DIAM. M
CELL BODY IN
THE LAMINA
PYRAMID COM-
PUTED DIAM.
NUCLEUS IN
GANOL. SI-IK.
COMP. DIAM.
NUCLEUS IN
THE LAMINA
PYRAM. COMP.
DIAM.
AGE
days
days
1
10.5
11.4
7.9
9.4
1
20
18.1
18.7
10.2
15.7
20
546
16.9
17.0
9.4
13.8
730
Ratio be-
ratio
tween 1 and
1 : 1.7
1 :1.6
1 :1.3
1 :1.3
of Ito
20 days
20
days
Ratio be-
ratio
tween 1 and
1 : 1.6
1 : 1.5
1 :1.2
1 :1.2
of Ito
546 days
730
days
Considering the course of growth in these cells, we find it to
be similar in both the spiral ganglion and the lamina pyramidalis
of the cerebral cortex (rat) as reported by Sugita ('18). In the
former the cells attain at twenty days of age, the time of wean-
ing, their maximum size, and then diminish slowly with advancing
age. The cells of the lamina pyramidalis also reach their full
size at twenty days, and then diminish in the same way. There-
fore, the course of the growth of both of these groups of nerve
cells coincides. However, I do not know of other instances
of the phenomenon. When tabulated, the relations here noted
appear as in table 106.
The difference between them is only in the absolute values
of the diameters of the cell bodies and especially of the nuclei,
138
the nuclei in the cells of the lamina pyramidalis being decidedly
larger than in those of the spiral ganglion. The ratios of in-
crease are, however, similar.
When we consider the increasing ratios of the diameters of
the ganglion cells, we see a close similarity in the maximum values
between the cells in the spiral and gasserian ganglion (Nittono,
'20). Nevertheless while in the former the ratios from 1 to 20
and 1 to 366 days are in the cell bodies 1:1.7 and 1 : 1.6, respec-
tively, in the latter the ratios for the corresponding intervals are
1: 1.43 and 1: 1.69, respectively (Nittono, '20, p. 235). In the
nucleus also similar relations are to be seen in both ganglia.
As these ratios show, there is in the gasserian ganglion a definite
increase in the diameters of cells and nuclei after 20 days of age;
the time when the maximum is reached by the cells of the spiral
ganglion. Thus the former continue to grow after growth in
the latter has ceased. These results suggest that the neurons in
the more specialized ganglia, like the spiral ganglion, may mature
earlier than do those in the less specialized.
On the correlation between the growth of the hair cells of the papilla
spiralis and of the nerve cells of the ganglion spirale. When we
compare the growth changes in the hair cells with those in the
ganglion cells, we find that the course of the development is
similar. Both classes increase in volume from one to twenty
days of age, then tend to diminish slowly the hair cells more
slowly than the ganglion cells. In the ratios of increase, however,
there are marked differences. Thus in table 67 (bottom of last
column) the volume ratios from 1 to 20 and 20 to 546 days are
1 : 2.4 and 1 : 0.9, respectively in the hair cells, and in the ganglion
cells, table 108, the ratios of the volumes in the fourth column
work out for the corresponding ages as 1: 5.1 and 1: 0.8, re-
spectively. In the case of the nuclei the growth changes are
somewhat different. In the hair cells the nucleus grows in
diameter more rapidly, and therefore reaches at nine days its
maximum value and then diminishes at succeeding ages.
I have sought to determine whether there was any correlation
in growth between either the entire cylindrical surface or the area
of the cross-section of the hair cells, on the one hand and the volume
139
of the cells of the ganglion spirale on the other. The reason for
making this comparison was the fact that Levi ('08), Busacca
('16), and Donaldson and Nagasaka ('18) have noted in the cells
of the spinal ganglia of several mammals that the postnatal
growth in volume was correlated with the increase in the area of
the body surface, and recently Nittono ('20) has found in the
rat a similar relation between the growth of the cells of thegasserian
ganglion and the area of the skin of the head. On examining
this problem, it is evident that the correlations thus far reported
TABLE 107
Comparison of ratios between the volumes of the cells of the ganglion spirale. nn<l ///
ratios of the area of the cylijidrical surface of the hair
cells of the organ of Corti on the maximum values
AOE
BOOT
WEIGHT
VOLUME OP 1 III
ClANllI.ION CELL,
/'
RATIOS ON
THE
MAXIMUM
VALUE
AKEA OF
CYLINDRICAL
SURFACE OF THE
HAIR CF.LLH- M *
1ATIO8 ON THE
MAXIMUM
VALUE
days
gms.
I
5
606
3105
1 :5.12
395
723
1
1.83
3
8
796
:3.90
463
1.56
6
11
1124
:2.76
582
1.24
9
10
1317
:2.36
648
1.12
12
13
1376
:2.26
681
1.03
15
13
1732
:1.79
729
0.99
20
29
3105
: 1.00
723
1.00
25
36
2903
: 1.07
691
1.05
50
59
2806
:1.11
697
1.04
100
112
2527
: 1.23
678
1.07
150
183
2439
:1.28
691
1.05
257
137
2483
: 1.25
689
1.05
366
181
2527
: 1.23
683
1.06
546
255
2527
: 1.23
699
1.03
apply to the postnatal growth period, and that we must consider
that the functional relations of the skin are well established,
even at the earliest age. The data with which we have worked in
the case of the cochlea are presented in several tables (107 to
110).
In tables 107 and 108 are given the volumes of the cells of the
ganglion spirale and the areas of the cylindrical surface of the
hair cells. In table 107 the ratios are computed by dividing the
maximum value by the values at each age, and in table 108 by
dividing the values at each age by the initial value.
TABLE 108
Comparison of the ratios of the volume of the cells of the ganglion spirals with the
ratios of the area of the cylindrical surface of the hair cells of the organ of
Corti on the initial values
AGE
BOOT
WEIGHT
VOLUME OF THE
GANGLION
CELLS M *
RATIOS ON THE
INITIAL
VALUE
AREA OF THE
CYLINDRICAL
SURFACE OF THI
HAIR CELLS M
RATIOS ON
, THE INITIAL
\ VALUE
days
grams
1
5
606 : 606
1
1.00
395
395
1
1.00
3
8
: 796
1.31
463
1.17
6
11
: 1124
1.85
582
1.47
9
10
: 1317
2.17
648
1.64
12
13
: 1376
2.27
681
1.72
15
13
: 1732
2.86
729
1.85
20
29
:3105
5.12
723
1.83
25
36
:2903
4.79
691
1.75
50
59
:2806
4.63
697
1.76
100
112
:2527
4.17
678
1.72
150
183
:2439
4.02
691
1.75
257
137
:2483
4.10
689
1.74
366
181
:2527
4.17
683
1.73
546
255
:2527
4.17
699
1.77
TABLE 109
Area of the cross-section of the inner and outer hair cells
WEIGHTED
DIAMETER OF
AVERAGE
DIAMETER OF
WEIGHTED
AGE
BODY
ONE INNER
DIAMETER OF
INNER AND
AREAS OF CROSS
WEIGHT
HAIR CELL
THREE OUTER
OUTER HAIR
SECTION OF
M
HAIR CELLS
CELLS
HAIR CELLS
M
M
M 2
days
grams
1
5
6.6
6.0
6.2
30
3
8
8.0
7.4
7.6
45
6
11
8.1
7.6
7.7
48
9
10
8.8
8.5
8.6
5S
12
13
8.5
8.3
8.4
55
15
13
8.4
7.7
7.9
50
20
29
8.8
8.2
8.4
55
25
36
8.8
8.1
8.3
55
50
59
8.8
8.2
8.4
55
100
112
8.6
8.1
8.2
53
150
183
8.5
8.3
8.4
55
257
137
8.5
8.3
8.4
55
366
181
8.8
8.4
8.5
58
546
255
8.6
8.2 | 8.3
55
GROWTH OF THE INNER EAR OF ALBINO RAT
141
I have calculated the cylindrical surface of the hair cells
according to the formula for the lateral surface of a cylinder;
therefore, this area equals 2 v r a (r = radius, a = height of the
cylinder) . As the hair cells are more or less pointed at their lower
end, the surface obtained by this formula has nearly the value of
the total surface of the hair cells less that for the upper end disk.
As has been already shown, both classes of cells grow rapidly
from birth to twenty days, and after that both tend to decrease
slightly in volume. It is evident that during the growing period,
TABLE 110
Comparison of the ratios of the volume of the cells of the ganglion spirale with the
ratios of the areas of the cross-section of the inner and outer hair cells
of the organ of Corti
AOE
days
BODY
WEIGHT
gms
VOLUME OF THE
GANGLION
CELLS M '
RATIOS ON THE
INITIAL
VALUE
AREA Or THE
CROSS-SECTION
OF THE HAIR
CELLS
RATIOS ON THE
INITIAL
VALUE
1
5
606
606
1
1.00
30 :30
1
1.00
3
8
796
1.31
:45
1.50
6
11
1124
1.85
:48
1.60
9
10
1317
2.17
:58
1 . 9
12
13
1376
2.27
:55
1.83
15
13
1732
2.86
:50
1.67
20
29
3105
5.12
:55
1.83
25
36
2903
4.79
:55
l s:;
50
59
2806
4.63
:53
1.77
100
112
2527
4.17
:53
1.77
150
183
2439
4.02
:55
1.83
257
137
2483
4.10
:55
1.83
366
181
2527
4.17
:58
1.93
546
255
2527
4.17
:55
1.83
from one day to the end of the record, the volumes of the ganglion
cells increase more rapidly than do the cylindrical areas of the
hair cells (table 108). If we seek a numerical expression of these
relations, it seems best to start not with the values at birth, but
with those at nine days of age when the cochlea is just beginning
to function, and to extend the comparison only up to twenty days
when both groups of cells have reached their maximum size.
Thus at nine days (table 108) the volume of the ganglion cells
is 1317 [A 3 , while at twenty days it is 3105 [A 3 , or as 1: 2.3, while
the area of the cylindrical surfaces of the hair cells at the respective
142 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
ages is 648 [x 3 and 723 [i 3 , or as 1 : 1.1, thus showing a rapid growth
of the ganglion cell bodies accompanied by but slight enlargement
of the hair cells.
It is evident from these ratios that the ganglion cells are
increasing in volume more rapidly than the hair cells in area.
It is possible that the nervus cochlearis innervates the other
cells of the cochlea as well, but even if this is taken into con-
sideration the general relations remain the same.
It follows from this that during the period between the earliest
appearance of the functional response (nine days) and the
attainment of the maximum size of the cells, the innervation
of the hair cells is steadily improving, if we may infer such an
improvement from the increase in the volume of the ganglion
cells. After the close of this early growing period the relations
are approximately fixed through the remainder of life. We do
not find, therefore, in the cochlea any relation which corres-
ponds to those found between the spinal ganglion cells or those
of the gasserian ganglion and the associated areas of the skin
during postnatal growth. This seems to indicate that in the
cochlea growth is fixed or limited, while in the body as a whole
it is more or less continuous, and the ganglion cells behave
differently in the two cases.
In table 109 are shown the diameters of the inner and outer
hair cells and their weighted diameters. In the last column
is given the area of the cross-section of the hair cells.
The ratios of these areas on the initial area are shown in table
110 in comparison with the volumes of the ganglion cells on the
initial volume, and indicate that from three days of age the
values for the ganglion cells are increasing more rapidly than
those for the area of the cross-section of the hair cells, and at
twenty days the increase in the case of both elements has reached
a maximum. Here, as in the case of the cylindrical surface,
both elements show like phases of growth, but the increase in
the volumes of the ganglion cells is much greater than the increase
in the cylindrical area or cross-section of the hair cells.
As it may be desirable to use for comparison the measure-
ments on the cells of the ganglion spirale as here reported, the
GROWTH OF THE INNER EAR OF ALBINO RAT
143
constants for the determinations based on 160 cells in each age
group are given in . table 111 for the radial vertical sections
and in table 112 for the cross-sections.
TABLE 111
A nalytical constants* giving the mean, standard deviation and coefficient of variability
unth their respective probable errors for the diameters of the cells and their
nuclei of the ganglion spirale in radial vertical section
AOK
days
FOR TOTAL NUMBER "K CELLS
Cell
Nucleus
Mean
Standard
deviation
Coefficient of
variability
1
Cell
10.2 0.05
0.90 0.03
8.9 0.33
Nucleus
7.8 0.02
0.46 0.01
5.9 0.22
3
Cell
11.3 0.03
0.50 0.02
4.4 0.17
Nucleus
7.9 0.02
0.32 0.01
4.1 0.15
6
Cell
12.6 0.04
0.68 0.03
5.4 0.20
Nucleus
8.4 0.03
0.48 0.02
5.7 0.22
9
Cell
13.1 0.03
0.61 0.02
4.7 0.18
Nucleus
8.5 0.03
0.52 0.02
6.1 0.23
12
Cell
13.4 0.05
0.86 0.03
6.4 0.24
Nucleus
8.4 0.03
0.61 0.02
7.3 0.28
15
Cell
14.6 0.04
0.73 0.03
5.0 0.13
Nucleus
8.7 0.03
0.58 0.02
6.7 0.25
20
Cell
17.8 0.06
1.17 0.04
6.6 0.25
Nucleus
10.0 0.02
0.40 0.02
4.1 0.15
25
Cell
17.3 0.05
0.88 0.03
5.1 0.19
Nucleus
9.9 0.02
0.36 0.01
3.6 0.14
50
Cell
17.2 0.04
0.78 0.03
4.5 0.17
Nucleus
9.7 0.02
0.34 0.01
3.6 0.14
100
Cell
16.5 0.03
0.65 0.02
3.9 0.15
Nucleus
9.4 0.02
0.38 0.01
4.0 0.15
150
Cell
16.4 0.03
0.79 0.02
4.8 0.18
Nucleus
9.1 0.02
0.42 0.02
4.6 0.17
257
Cell
16.6 0.06
1.09 0.04
6.6 0.25
Nucleus
9.5 . 02
0.39 0.01
4.1 0.15
366
Cell
16.7 0.05
1.02 0.01
6.1 0.22
Nucleus
9.3 0.03
0.52 0.02
5.6 0.21
546
Cell
16.7 0.06
1 . 06 . 04
6.4 24
Nucleus
9.3 0.02
0.45 0.02
4.9 is
Conclusion. For the study of the growth of the nerve cells
in the ganglion spirale fourteen age groups were taken and the
data obtained from the 160 largest cells in each age group.
Besides these, six age groups, representing six cochleas, were
examined in cross-sections to determine the form of the ganglion
144
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
cells and the relation of their long axes to the axis of the cochlea.
Here also the ten largest cells in each of four, nearly corre-
sponding turns, were measured. We obtained the following
results :
1 . As thus prepared, the ganglion cells at birth have a maximum
size of 11 x 10 [i in cell body and 8.2 x 7.6 [x in nucleus. At
twenty days the diameters are the largest, 18.7 x 16.9 [x in cell
body and 10.3 x 10.0 [x in nucleus.
TABLE 112
Analytical constants giving the mean, standard deviation and coefficient of vari-
ability with their respective probable errors for the diameters of the cells
and their nuclei of the ganglion spirale, in cross-section
AGE
CeU
Nucleus
FOB TOTAL NUMBER OP CELLS
Mean
Standard
deviation
Coefficient of
variability
days
15
Cell
14.7 0.04
0.40 0.03
2.7 0.21
Nucleus
8.9 0.04
0.34 0.03
3.8 0.29
20
Cell
17.1 0.09
0.83 0.06
4.9 0.37
Nucleus
10.0 0.06
0.58 0.04
5.8 0.44
25
Cell
17.1 0.07
0.63 0.05
3.7 0.28
Nucleus
9.8 0.03
0.30 0.02
3.1 0.23
100
Cell
16.7 0.05
0.44 0.03
2.6 0.20
Nucleus
9.6 0.04
0.36 0.03
3.7 0.25
150
Cell
16.4 0.07
0.69 0.05
4.2 0.32
Nucleus
9 . 4 . 05
. 46 . 03
4.9 0.37
371
Cell
16.0 0.06
0.55 0.04
3.5 0.24
Nucleus
9.1 0.05
0.43 0.03
4.7 0.36
2. The ganglion cells grow relatively rapidly after birth and
reach at twenty days of age their maximum size. After having
passed the maximum at twenty days, they diminish in size
very slowly, but the internal structure matures more and more
with successive age.
3. The nuclei are relatively large at birth but increase more
slowly than the cell bodies do; nevertheless, they follow the
same course of development as the latter. This peculiar course
in the growth of the ganglion cells is similar to that followed
by the cells of the lamina pyramidalis of the cerebral cortex
of the rat as found by Sugita ('18)
GROWTH OF THE INNER EAR OF ALBINO RAT 145
4. Within the cochlea the cell bodies and nuclei increase
their diameters from the base toward the apex, except in the
earlier stages.
5. There are no evident differences in the diameters of the
cell bodies and the nuclei of the ganglion cells either according
to sex or side.
6. Both the cell bodies and the nuclei are immature at birth,
but differentiate rapidly, and even at six days the Nissl bodies
are visible. The differentiation proceeds with advancing age.
7. The ganglion cells are bipolar and oval in shape. The
direction of the long axis of the cells differs according to the
turn of the cochlea and in the upper turn it runs almost parallel
to the axis of the modiolus but inclines more and more to the
horizontal position on passing to the base.
8. The nucleus-plasma ratios of the ganglion cells increase
with age in both the radial and cross-sections.
9. The increase in the volume of the ganglion cells and the
area of the cross-section of the hair cells is approximately sim-
ilar during the first nine days of life, but after that the ganglion
cells increase relatively very rapidly. These relations are very
different from those found for the spinal ganglion cells by Don-
aldson and Nagasaka ('18) and for the cells of the gasserian
ganglion by Nittono ('20).
The nervus cochlearis innervates not only the hair cells, but
all the elements of the cochlea, and this may have some in-
fluence upon this relation. It is interesting to note that the
rate of increase in the cylindrical surface of the hah* cells is
similar to that in the area of the cross-sections of these same
cells.
II. CORRELATION BETWEEN THE INCEPTION OF HEARING
AND THE GROWTH OF THE COCHLEA
The present study aims merely to compare in the rat the
size of each element of the cochlea just before and just after
the appearance of hearing and to ascertain the changes in the
cochlea which take place during this phase. The rats which
have sense of hearing show the so-called ' Ohrmuschelreflex '
146 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
of Preyer and other responses to auditory tests. Both the guinea-
pig and rat react most evidently to sounds. The former animal
responds usually five to six hours after birth. In the rat, however,
the development of the function is, as already stated, relatively
retarded and usually first appears at about ten days of age.
To test the presence of hearing there are several methods,
as for example, Preyer V Ohrmuschelreflex' and the reflex
closure of the eyelid, and these I used in making my observations.
As the source of the sound I selected the hand clap, a whistle
(Triller-pfeife, about c 4 ) and a low sound made by drawing in
the breadth with nearly closed lips (about c 1 ).
Since it is my purpose merely to determine the first appear-
ance of a response to sound, it is not nescessary to carry out such
refined examinations as did Hunter ('14, '15, '18) Watson
('07), and others on white rats, and Marx ('09) on the guinea-
pig, nor was it necessary to use the tuning-fork which by the
way is not so good for tests on animals as for those on man.
Since sometimes we may have a defect of hearing in animals,
as shown by many investigators, it was deemed necessary to
use several sources of sound and to take care not to produce
ah* currents striking the test animal or to touch it in any way.
For this purpose a large sheet of glass was placed between the
source of sound and the rats to be tested. While the rat was
resting I suddenly produced the sound and noted whether the
rat responded. When the animals already had their eyes open
the test was made from behind to avoid visual reflexes.
Observations
Rats at birth show no response to auditory stimuli. Most
of them respond at twelve days of age very clearly, sometimes
at ten to eleven days Under certain circumstances, the time
of the reflex can be rather accurately noted. For example,
while in the morning at ten days no reflex was noted it was
present in the evening of the same day. Fortunately, I obtained
five nine-day-old rats belonging to one litter and in nearly the
same condition of nourishment and developnent. One of these
GROWTH OF THE INNER EAR OF ALBINO RAT 147
responded to the test very evidently at noon on the ninth day,
but the others did not. The sound which was effective was
fairly intense, but to a faint and low-pitched sound this rat
did not respond. In this case the external auditory canal was
open. In the others there was in some a small open canal,
but more or less closed by a cellular plug. In the latter cases
I removed this obstruction without much difficulty or damage
by washing, yet no reaction could be obtained to the stimuli.
As it was to be expected, that also in the latter the reflexes would
very shortly appear, all the cochleas of these young rats, both
the not-hearing and hearing, were fixed by the method pre-
viously described and later examined.
In chapter 1, in which I followed the growth changes in the
constituents of the membranous cochlea and in its ganglion
cells from birth to maturity, including ' not hearing ' and ' hearing '
rats, very evident differences were observed in rats between
nine and twelve days of age. In view of this, it will be of in-
terest to compare the measurements obtained from the 'not
hearing' and 'hearing' rats nine days old and members of the
same litter. From the differences thus obtained we can conclude
concerning the developmental changes in the cochlea requisite
for the first appearance of hearing, provided there are no obstacles
in the sound-conducting apparatus or deficiencies in the central
organ.
In table 113 are given the values for the size of the several
constituents of the cochlea 'from a rat which did not hear and
one which did, at nine days. The former data are the averages
from four cochleas, while the latter are from two. The table
shows in a striking way that where there is a significant differ-
ence. The values obtained from the rat which could hear are
usually larger than those of the rat which could not hear.
Among these measurements we see sometimes very marked
and sometimes only slight differences. Only the radial distance
between the labium vestibulare and the inner edge of the head
of the inner pillar cell in the first two turns and the diameter of
the nuclei of the inner and outer hair cells are in the former smaller
than in the latter. In both instances, however, these smaller
148
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
TABLE 113
Comparison of the dimensions of the constituents of the cochlea in a hearing rat (H.)
with those in a rat not hearing (N.) at nine days of age measurements
in micro
BAT
AGE
BODY
WEIGHT
(N.)
(H.)
days
9
9
grams
10
11
(N.)
(H.)
1430
1434
Average
distance between two spiral ligaments
Breadth of membrana tectoria
TURN I
II
III
IV
Average
Th ids ness
(N.)
(H.)
243
242
270
268
304
308
306
314
281
283
27
27
Breadth of membrana basilaris
TURN I
II
III
IV
AVERAGE
ZONA ZONA
ARCUATA PECTINATA
(N.)
(H.)
169
171
189
186
202
214
201
204
191
196
79 112
93 103
Distance between the habenula perforata and the outer corner of the inner
hair cell
TURN I
II
III
IV
AVERAGE
(N.)
(H.)
38
40
38
42
44
58
49
60
42
50
Distance between habenula perforata and the outer corner ol the outer pillar
cell at foot*
TURN I
II
ill
IV
Average
(N.)
(H.)
70
79
76
88
86
103
86
102
79
93
Height of greater epithelial ridge
TURN I
II
III
IV
AVERAGE
(N.)
(H.)
36
42
40
43
41
48
42
50
40
46
Distance between the labium vestibulare and the habenula perforata
TURN I
II
III
IV
Average
(x.)
(H.)
83
85
108
104
137
140
145
150
118
120
GROWTH OF THE INNER EAR OF ALBINO RAT
149
TABLE 113 Continued
Distance between the labium vestibulare and the inner edge of the head of the
inner pillar cell
TURN I
II
III
IV
Average
(N.)
(H.)
94
78
131
108
168
170
179
210
143
142
Height from basal plane to surface of pillar cells
TURN I
II
III
IV
AVERAGE
(N.)
(H.)
32
40
33
42
35
45
36
45
34
43
Height of tunnel of Corti
TURN I
II
III
IV
AVERAGE
(N.)
(H.)
20
18
14
11
16
Height of papilla spiralis at the third series of outer hair cells
TURN I
II
III
IV
AVERAGE
(N.)
(H.)
28
42
28
43
27
39
28
36
28
40
Height of Hensen's cells
TURN I
II
ill
IV
AVERAGE
(N.)
(H.)
20
42
23
45
23
38
24
30
23
39
Angle of lamina basilaris with plane of membrana basilaris degrees
TURN I
II
HI
IV
AVERAGE
(N.)
(H.)
+7
+4
-8
7
Length of the inner and outer pillar cells
INNER
TURN I
II
III
IV
AVERAGE
(N.)
(H.)
35
36
39
39
41
42
40
45
39
41
OUTER
TURN I
II
III
IV
AVERAGE
WEIGHTED
AVERAGE
(N.)
(H.)
26
45
26
54
29
50
29
40
28
47
30
46
Volume of inner and outer hair cells
INNER: AVERAGE
OUTER: AVERAGE
WEIGHTED AVERAGE
(N.)
(H.)
1798
1815
1277
1279
1407
1428
150
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
TABLE 113 Concluded
Diameter of nuclei of the inner and outer hair cells
INNER: AVERAGE
OUTER: AVERAGE
WEIGHTED AVERAGE
(N.)
(H.)
8.3
8.2
8.0
7.4
8.1
7.6
DEITERS' CELLS:
VOLUME M '
DIAMETER OF
NUCLEI
LENGTH OF CELL
BODY
PHALANGEAL
PROCESS
(N.)
(H.)
518
1193
7.0
7.2
14
32
22
22
Ganglion spirale: diameters computed
CELLS
NUCLEI
(N.)
(H.)
13.6
13.7
8.5
8.6
values are marks of maturity. These changes in size accord
with the results given in chapter 1 at twelve days of age, though
there are some differences between them in the absolute values.
Figures 7 and 8 illustrate the outlines of the tympanic wall
of the membranous cochlea in nine-day-old rats which could
not and could hear, respectively. These figures have been
drawn from the corresponding sections at the beginning of
the middle turn of the cochlea and are comparable with figures
3 to 6 and 9 to 12. On comparing figures 7 and 8, the more
noticeable differences appear to be the following.
The membrana tectoria is a bit longer in the hearing rat.
The appearance and the position of it with reference to the
surface of the papilla spiralis is also different. In the not-hearing
cochlea it has an infantile look.
The outer end of the main part does not yet reach the second
row of the outer hair cells and connects with the Hensen's
prominence by a thick thread. There are also many fine fibers
to be seen between the basal surface of the membrane and the
papilla. In the hearing rat the fine fibers are absent. The
membrane reaches already the row of the outer hair cells and
there is a strong connection between this part and the terminal
ame (Schlussrahmen) of the lamina reticularis by a thick
read as shown in figure 8 Thus the position of the membrane
GROWTH OF THE INNER EAR OF ALBINO RAT 151
above the papilla depends a little bit upon the increase of
the length of the membrane itself, but chiefly upon other factors
such as the inward shifting of the papilla. The membrana
basilaris as a whole shows a small increase o" breadth in the
hearing rat. The zona arcuate, however, increases much in
its breadth, while the zona pectinata rather decreases. This
is due to the development of the pillar cells. The base of the
inner and outer pillar cell spread much on the membrane. At
the same time the length of the cells, especially of the outer,
increases nearly twice as much as in the not-hearing rat.
Thus the foot of the outer pillar cell moves out ward, as Bottcher
('69, 72) stated, while the inner corner of the inner pillar cell
does not move in any way, as the habenula perforata stands at
a fixed point. This results in a change in the form of the arch
of Corti. The hitherto outward inclined arch tends to bend
inward and between both inner and outer cells arises a space,
the tunnel of Corti. The appearance of the tunnel seems to have
some relation to hearing. The tunnel is always present in the
cochleas of hearing rats. Sometimes the tunnel is present in
the lower turns, but not in the upper turns in the not-hearing rats.
We can say, therefore, that it probably appears through all the
turns before the special function of the cochlea begins. In this
way the zona arcuata of the membrana basilaris increases its
breadth.
The next striking change is the rapid increase in the size of
the Deiters' cells, Hensen's cells, and the resultant change of
the form, with an inward shifting, of the papilla spiralis.
The Deiters' cells increase their height very rapidly; the length
of the cell body becomes over twice that in the not-hearing rat,
but the processus phalangeus changes only slightly. Hen-
sen's cells develop also, but not so much as Deiters' cells. The
papilla spiralis thus increases in height. On the other hand,
the greater epithelial ridge vanishes inwards from the inner
supporting cells and appears as a furrow the sulcus spiralis
internus. Through the pressure of these outward-lying cells
the papilla spiralis swings inward as a whole, without really
moving on the membrana basilaris. The lamina reticularis
152 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
becomes inclined inward instead of outward and subtends a
slight angle with the plane of the membrana basilaris. The
distance from the labium vestibulare to the inner edge of the
head of the inner pillar cell becomes smaller through the inward
shifting of the papilla.
In the hair cells and the cells of the ganglion spirale we see
a smaller difference between the hearing and not-hearing rats.
Only the diameter of the nuclei of the hair cells in the hearing
rat diminishes a little, as it continues to do in the adult cochlea.
All the changes just enumerated begin at the base of the
cochlea and progress to the apex. Therefore we see the high
and outward ascending papilla spiralis in turn I, while in the
upper turns the papilla is not yet so developed, is smaller in all
the constituents, and shows in general the characters of a younger
and less mature cochlea conditions which disappear with age.
This upper and immature part seems not to respond to the test
for hearing. Indeed, my testing result is positive for sounds of
high pitch, but not for low pitch. Therefore we conclude that
the papilla spiralis develops functionally from base to apex and
that when the papilla spiralis has developed in the basal turns,
but not in the upper turns, it responds to sounds of high pitch
alone.
Discussion
If we assume that our tests for hearing are trustworthy, then
the differences between the size of the constituents of the cochlea
in nine-day-old rats which could and could not hear will indicate
what developmental changes in the cochlea of the albino rat are
necessary for the appearance of the hearing reflex. Whether all
the differences found by us are necessary is difficult to determine,
and the problem is open for further study; but as the matter
stands, our results give the closest correlation between structural
changes and the appearance of function which has as yet been
reported.
Kreidl and Yanase ('07) studied the differences between the
not-hearing and hearing rat and summarized their results on
page 509: "Kurz vor Eintritt des Horreflexes ist das Cortische
GROWTH OF THE INNER EAR OF ALBINO RAT 153
Organ im wesentlichen fertig ausgebildet. " They publish no
measurements nor data. The condition of the development of
the organ of Corti described as 'fertig ausgebildet' is not suffi-
ciently precise.
Further, on the same page they say, "Der auffalligste und,
soweit die Untersuchungen bis jetzt eregben haben, einzige
Unterchied, der zwischen dem anatomischen Bild des Labyrinthes
eines neugeborenen Tieres, das den Reflex eben nochnichtaufweist,
und dem eines solchen, dasdenselben zum ersten Male eben erkenn-
an lasst, ist der, dass beim ersteren noch ein Zusammenhang zwis-
chen Cortischem Organ und Cortischer Membran besteht, beim
letzteren dagegen dieser Zusammenhang bereits gelost oder gelock-
ert ist." Their observation is quite different from mine. In my case
the papilla spiralis shows in the development of its constituent
elements pretty large differences between the not-hearing and
hearing rats. Therefore it seems probable that the changes in the
growth and form of the papilla just before the first appearance of
the special function, take place very quickly. Also we cannot
agree to then* statement concerning the relation of the membrana
tectoria to the papilla spiralis. In our preparations there is
still a connection of the membrane with the terminal frame of the
lamina reticularis through a thick thread in the cochlea of the
rat which could hear (fig. 8) and also in that of the rat which
could not hear (fig. 7).
This is a point on which opinions differ. While one opinion,
represented by Kishi ('07) and others, is to the effect that this
connection remains through life, the other, represented by Koll-
iker('67) and others, asserts the membrane projects free in the
endolymph. I have never seen this connection in the adult
cochlea, nor have I found such a connection of the membrane
with the hairs of the hair cells, as Shambaugh ('10) described in
the pig. In the young rats, at fifteen days for example, we very
often see upon the terminal frame the broken remainder of this
connecting thread. Whether this break arises through natural
development or is the result of artificial manipulation it is hard
to say. At any rate, Held's assertion ('90), that in an animal
capable of hearing the membrana tectoria is never connected
154 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
with the papilla spiralis, is not supported by my observation.
That the freeing of the outer zone of the membrane is not ab-
solutely necessary for the mediation of auditory impulses is
demonstrated in the cochlea of birds, as shown by Hasse ('66),
Retzius ('84), Sato ('17), and others. In these forms the mem-
brane remains through life attached to the epithelial ridge.
My results agree with those of Hardesty ('15) on this point,
though he obtained a tectorial membrane which floats free in
the endolymph with its outer zone. Lane ('17) studied the cor-
relation between the structure of the papilla spiralis and the
appearance of hearing in the albino rat, but his description is
brief and does not touch on this relation of the papilla to the
tectorial membrane.
Thus the inception of hearing does not coincide with the
detachment of the tectorial membrane from the papilla spiralis,
but with the development of each constituent of the papilla
spiralis and the membrane tectoria, as has been described. As
these changes occur first at the base and then pass to the apex,
the animal can perceive at first only the sounds of high pitch.
One or two days later development is complete in all the turns,
and then the rat can hear the sounds of lower pitch also. Thus
the process of the development of the cochlea does not support
the ' telephone theory' of audition, but on the contrary agrees with
the conclusion that the papilla in different locations in the turns
of the cochlea responds to sounds of a definite pitch, as Witt-
maack ('07), Yoshii ('09), Hoessli ('12), and others have shown
by experimental studies on the mammals.
Concerning the exact age of the first appearance of the function
in the rat, there are several different statements. Lane ('17)
found no response to sound before the twelfth day after birth,
and on the sixteenth day he reports hearing well established.
Kreidl and Yanase ('07) state that hearing begins in the rat at
from twelve to fourteen days. My rats responded usually at
ten to twelve days, but one at nine days. These differences
depend in all probability on the vigor of the young during the
first days of postnatal life, and it seems probable that exception-
ally well-nourished young might develop precociously in this
GROWTH OF THE INNER EAR OF ALBINO RAT 155
respec t. The intensity of the stimulus is important in determining
the hearing reflex, as Small ('99) has stated. In my cases the
young rats responded very evidently to intense sounds, while
they reacted weakly or not at all to those which were faint.
Thus only the intense sounds were perceived by the rat of nine
days.
Conclusions
1. The hearing reflex was never obtained in rats less than
nine days of age.
2. At nine days a single rat, one of five in a litter, responded to
a sharp sound like clapping the hands and to a whistle of high
pitch; the other four did not respond. At the tenth day some
of the four reacted, and at the twelfth day all could hear.
3. The hearing reflex probably occurs early in young rats
that are vigorous and well nourished.
4. To obtain the first hearing reflexes it is necessary to have
rather strong sounds of high pitch.
5. A comparison of the histological structure of the cochlea
in rats of nine days, one of which could hear and the other could
not, shows clear differences in its development of the cochlea.
These consist not in the detachment of the tectorial membrane
from the papilla spiralis, but in the degree of differentiation of
the constituents of the papilla. The tectorial membrane is
connected in both cases at its outer end with the terminal frame
of the lamina reticularis by a thick thread. The papilla is more
differentiated in the hearing rat in several characters. The
tectorial membrane has reached with its outer end the outermost
row of the outer hair cells, but in the not-hearing rat it has not
yet reached the second row of the cells.
6. The form of the papilla and its relation to the surrounding
structures, especially to the tectorial membrane, are in the hearing
rat at nine days very similar to those in the rat at twelve days
of age, though there are some differences between them in ab-
solute size.
7. The freeing of the tectorial membrane from the papilla
spiralis is not necessary to the appearance of the hearing reflex,
156 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
but the differentiation of the papilla, its shifting inward, its
change in form and position under the membrana tectoria, appear
to be important.
8. Since the papilla develops from the base toward the apex, it
first reaches in the lower turn a high degree of differentiation,
and this part first begins to function. Therefore the rat can
hear only sounds of high pitch when it first responds.
9. This result accords with that well-known fact that the
papilla in the lower turn responds to sounds of a high pitch,
while in the upper turn it responds to sounds of low pitch.
III. ON THE GROWTH OF THE LARGEST NERVE CELLS
IN THE GANGLION VESTIBULARE
Material and technique
The material used for the present study was in a great part the
same that was employed for the studies reported in chapter 1,
with the addition of some new specimens as shown in table 114
and table 94. In the slides obtained in the radial vertical section
we see the vestibular ganglion cells situated in a single group
at the radix of the cochlea (Fig. 3 G. V.). As four ears were used
in each age group, four cell groups were examined at each age.
Besides these fourteen age groups, six rats used for cross-sections,
in chapter 1, were also included.
The measurements were made in the same way and under
the same conditions as those described earlier for the cells of
the spiral ganglion. Since the ganglion vestibulare consists of
two parts, the ganglion vestibulare superius and inferius, the ten
largest cells were taken from each part and the results averaged.
Observations
By way of introduction I wish to say a word about equilibration
in the young rat. The young just born crawl over on each other
and seem to attempt to find the mothers nipples. They turn
the head to and fro and roll over on the flanks, belly, or back.
While resting they take their normal position or lie on the side.
When turned on their backs they endeavor to regain the normal
GROWTH OF THE INNER EAR OF ALBINO RAT
157
position. The fore legs are of more use than the hind in making
readjustments. The tails hang down between the hind legs.
TABLE 114
Data on rats used for the study of the cells of the ganglion vestibulare (radial section).
See also table 94
AOB
BOOT
WEIGHT
BODY
LENGTH
BEX
BIDE
AUDITOHT
RESPONSE
days
grams
mm.
1
5
44
9
R.
4
44
9
R.
5
48
d 1
R. L.
3
9
60
<?
R. L.
8
56
9
R. L.
6
10
64
a
R.
10
64
9
R. L.
11
62
(7
R.
9
11
67
<?
R. L.
+
9
58
9
R.
10
57
tf
R.
12
13
70
d 1
R. L.
+
12
68
9
R.
+
15
72
c?
R.
+
15
13
74
d"
R. L.
+
14
75
9
R. L.
+
20
30
.96
d 1
R. L.
+
28
94
c?
R. L.
+
25
34
101
9
R. L.
+
34
100
d 1
R. L.
+
50
58
121
9
R. L.
+
43
104
(f
R. L.
+
100
146
176
c?
L.
+
103
154
9
L.
+
101
152
9
R. L.
+
150
154
184
9
R. L.
+
189
191
c?
R.
+
199
192
d 1
R.
+
260
137
162
9
R.
+
140
171
9
R. L.
+
134
178
9
R.
' +
367
205
202
rf
L.
+
170
182
9
L.
+
179
196
9
R. L.
+
546
282
222
d 1
R. L.
+
227
204
d 1
R. L.
+
At three days they move and crawl very actively. They
tend to assume the normal position. When rolled over on the
back or side they succeed in regaining the normal position in
158
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
a few seconds. When six days old the rats have fairly well
coordinated movements. They use their fore and hind legs
effectively and in the same way. When the mother 's body touches
them they respond quickly by searching for the nipples.
At nine days they move much more quickly and the movements
are well coordinated. .Though the eyes are still closed, they
TABLE 115
Diameters of the cells and their nuclei in the ganglion vestibulare in radial vertical section
(Chart 43)
AGE
BODY
WEIGHT
DIAMETERS IN M
CELL BODY
NUCLEUS
Long
Short
Computed
Long
Short
Computed
days
grams
1
5
21.2
19.5
20.3
12.4
11.1
11.7
3
9
23.7
22.2
22.9
12.5
11.6
12.0
6
11
24.0
22.1
23.0
12.3
11.9
11.9
9
10
24.8
23.0
23.9
12.5
11.6
12.0
12
13
24.9
23.0
23.9
12.5
11.7
12.1
15
13
24.8
23.0
23.9
12.5
11.6
12.0
20
27
25.0
23.3
24.1
12.3
11.6
11.9
25
34
25.2
23.6
24.4
12.5
11.8
12.1
50
50
25.6
23.6
24.5
12.5
11.6
12.0
100
112
25.5
23.9
24.7
12.8
11.9
12.3
150
174
25.4
23.5
24.4
12.8
11.6
12.2
260
138
25.8
23.4
24.6
12.4
11.7
12.0
367
184
26.2
24.9
25.5
12.9
11.8
12.3
546
255
26.5
24.2
25.3
12.8
11.8
12.2
Ratios 1-
-367 days
1 1.3
1:1.1
1546 "
1.2
:1.0
15367 "
1.1
:1.0
crawl toward the object sought. When turned over on the back
they regain the normal position immediately. While resting they
lie on their bellies with all the legs spread well apart.
Twelve-day-old rats, though the eyes are still closed, go to
and fro actively with good coordination, but are somewhat slower
than the adults. The body loses its fetal red color through the
development of the first hairs. After this period the rats do
not differ greatly from the adult in their general behavior.
GROWTH OF THE INNER EAR OF ALBINO RAT
159
The growth changes in the ganglion cells of the ganglion vestibulare.
In table 115 (chart 43) are given the values for the diameters
of the cell bodies and their nuclei in the largest cells of the gang-
lion vestibulare. At the bottom of the last column for the cell
body and for the nucleus, respectively, are recorded the ratios at
1 to 367, 1 to 546, and 15 to 367 days. The last ratio was taken
25
a
20
15
10
*GEDAYSH
25
50
5O 1OO 2OO 30O 4OO 5OO
Chart 43 The diameter of the largest cell bodies and of the nuclei from
the ganglion vestibulare. table 115.
Cell bodies. -.-.-.-.-. Nuclei.
to facilitate a comparison with the data in table 118 which begin
at 15 days.
Looking at the ratios of the cell bodies and of their nuclei
from 1 to 546 days, it appears that the ganglion cells increase 1.2
in diameter, while their nuclei have only a very slight increase,
and therefore the ratio is 1 : 1.0. This increase in the cell bodies
is continuous from birth to old age, but after fifteen days is
very slow. In the nucleus we see a slight increase at the earlier
160 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
ages, after which the values are nearly constant. This means
that after birth the size of the cell bodies and their nuclei does
not increase so much as do those of the spiral ganglion cells,
or, expressed in another way, the cells in the vestibular ganglion
have developed earlier than those of the spiral ganglia and at
birth have already attained nearly their full size.
On the comparison of the diameter of the cell bodies and their
nuclei in the nerve cells of ihe ganglion vestibulare according to sex.
For this purpose twelve age groups of albino rats were used.
In seven cases we have two cochlea in each group in the same sex,
in which the average value is recorded. In table 116 are entered
the values for these diameters and at the foot of the table the
data are analysed. They reveal no evidence of a significant
difference in the diameters according to sex.
On the comparison of the diameters in the cell bodies and nuclei
of the nerve cells in the ganglion ves ibulare according to side. For the
present study fourteen age groups were employed. As indicated
in table 117, the data in five instances are based on the average
of two cochleas of the same side. Table 117 enables us to make
the comparison of the diameters of the cell bodies and their
nuclei on both sides, and the analysis of the data given at the
bottom of the table shows that there is no difference in these
characters according to side.
On the morphological changes in the cells of the vestibular ganglion.
Figure 14 illustrates semi-diagrammatically the ganglion cells
in the vestibular ganglion of the albino at birth, 20 and 367 days
of age. These figures, as in the ganglion spirale, have been
magnified 1000 times and the absolute values of the diameters
are given in table 115.
As seen in figure 14, both the cell body and the nucleus are at
birth already well developed and more precocious in their develop-
ment than the cells in any of the other cerebrospinal ganglia
thus far examined. The cytoplasm is relatively abundant and
the Nissl bodies are present, though both of these characters
become more marked later.
The nucleus is also large, the chromatin somewhat differentiated
and the so-called 'Kernfaden' often occur. Generally speaking,
I Day
20 Days
14
366 Days
Fig. 14 Showing setrii-diagrammatically the size and the morphological changes in
the ganglion cells in the ganglion vestibulare of the albino rat at the age of 1, 20 and 366
days. All cell figures have been magnified 1000 diameters.
GROWTH OF THE INNER EAR OF ALBINO RAT
161
therefore, the cells have the characteristics of the mature elements
though they stain less deeply than in the adult. At twenty days
of age the cell body is enlarged and fully mature. The Nissl
TABLE 116
Comparison of the diameters of the cells and their nuclei in the ganglion vestibidare
according to sex
AGE
BODY
WEIGHT
NUMBER OF
RATS
8EX
COMPUTED DIAMETERS
Cell body
Nucleus
days
grams
1
6
2
f
20.8
11.9
9
19.9
11.5
3
9
2
tf
21.7
11.8
8
2
9
23.8
12.2
6
11
2
tf
22.7
11.9
10
2
9
23.1
12.1
9
11
1
d*
23.8
12.5
9
1
9
23.8
12.1
12
15
1
cf
24.4
12.2
12
1
9
23.1
11.9
15
13
2
cf
24.3
12.2
13
2
9
23.4
11.9
20
30
1
cf
24.7
11.9
19
1
9
24.6
12.6
25
34
2
d"
24.4
11.9
34
2
9
24.4
12.4
50
43
2
cT
26.1
12.4
58
2
9
22.6
11.4
100
146
1
<?
26.3
12.8
103
1
9
23.4
12.6
150
194
2
rf 1
24.4
12.5
154
2
9
24.4
12.0
365
205
1
<f
24.2
11.7
170
1
9
24.6
12.1
Average for male
24.0
12.1
Average for female
23.4
12.1
Males larger
6
7
Females larger
3
5
Males and females equal
3
bodies are more differentiated and the nucleus is mature, though
it shows only a slight increase in size.
At 367 days the histological structures appear much as at
twenty days, but the diameters of both the cell body and the
nucleus have very slightly increased. This is in contrast to
the change which occurs in the cells of the spiral ganglion.
162
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
In order to study the form of the cells of the ganglion vestibulare
the measurements also were made on the cross-sections. Table
TABLE 117
Comparison of the diameters of the cells and their nuclei in the ganglion vestibulare-
according to side
AGE
BODY
WEIGHT
NUMBER
OF RATS
SIDE
COMPUTED DIAMETERS
Cell body
Nucleus
days
grams
1
4
1
R.
20.1
12.0
5
1
L.
22.0
12.5
3
9
2
R.
23.0
11.8
L.
22.6
12.3
6
10
1
R.
23.2
12.1
L.
23.5
12.0
9
11
1
R.
25.1
12.3
L.
23.8
12.5
12
15
1
R.
24.4
12.2
13
1
L.
25.1
12.5
15
13
2
R.
24.2
12.2
L.
23.6
11.9
20
30
1
R.
24.7
11.9
L.
23.5
11.4
25
34
2
R.
23.9
12.1
L.
24.9
12.2
50
50
2
R.
23.1
11.6
L.
25.6
12.3
100
101
1
R.
25.0
12.0
L.
24.8
11.7
150
199
1
R.
25.1
12.8
154
1
L.
25.4
12.5
263
140
1
R.
26.5
12.3
L.
25.1
12.4
368
179
1
R.
27.2
12.6
L.
26.2
13.0
546
255
2
R.
26.0
12.4
L.
24.6
12.0
Average right side
24.4
12.2
Average left side
24.3
12.2
Right larger
8
6
Left larger
6
8
118 (chart 44) shows the results. Looking at the ratios of 15 to
371 days, we see the same rate of increase in the cell bodies and
the nuclei as that in the radial section; i.e., in the cell bodies
1 : 1.1 and in the nuclei 1 : 1.0. Comparing the diameters at each
GROWTH OF THE INNER EAR OF ALBINO RAT
163
TABLE 118
Diameters of the cell bodies and their nuclei in the ganglion vestibulare, on cross-
section (chart 44)
DIAMETERS M
AOK
BOOT
WEIGHT
CELL BODY
NUCLEUS
Long
Short
Computed
Long
Short
Computed
days
grams
15
20
25.1
22.8
23.9
12.4
11.6
12.0
20
27
25.2
23.4
24.3
12.5
11.7
12.1
25
39
25.2
24.0
24.6
12.3
12.0
12.1
100
95
26.6
24.7
25.6
12.8
11.8
12.3
150
169
26.7
24.7
25.7
13.0
11.7
12.3
371
220
26.8
25.3
26.0
12.8
11.8
12.3
Ratio 15-371 days 1:1.1
1 :1.0
25
20
15
10
25
50
50 10O 20O 300 40O 5OO
Chart 44 The diameters of the cell bodies and of their nuclei from the
ganglion vestibulare, after fifteen days (cross-section), table 118.
Cell bodies. -.-.-.-.-. Nuclei.
164
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
age in both the radial and cross-sections, they are almost the
same, with a slight tendency for the cells in the cross-section to
give higher values, which suggests that the long axes of these
cells tend to lie in the plane of the section.
On the nucleus-plasma relations of the ganglion cells in the gan-
lion vestibulare. In table 119 are entered the computed diameters
of the cell bodies and their nuclei in the radial section, and in
the last column the ratios of the volume of the nucleus to that of
the cytoplasm obtained by the method previously given. As
TABLE 119
Nucleus-plasma ratios of the cells in the. ganglion vestibulare radial vertical section
COMPUTED DIAMETERS M
AGE
BODY WEIGHT
Cell body
Nucleus
Nucleus-plasma
ratios
days
1
grams
5
20.3
11.7
1 :4.2
3
9
22.9
12.0
:5.9
6
11
23.0
11.9
:6.2
9
10
23.9
12.0
:6.9
12
13
23.9
12.1
:6.7
15
13
23.9
12.0
:6.9
20
27
24.1
11.9
:7.3
25
34
24.4
12.1
:7.2
50
50
24.5
12.0
:7.5
100
112
24.7
12.3
:7.1
150
174
24.4
12.2
:7.0
260
138
24.6
12.0
:7.6
367
184
25.5
12.3
:7.9
546
255
25.3
12.2
:7.9
seen, the ratio is at birth relatively large, 1 : 4.2, and this increases
with age, in the earlier stages considerably, but in the later, less
rapidly. In the oldest age group it is largest, 1: 7.9.
On the cross-section the nucleus-plasma ratio is also progressive
and the increase is very regular (table 120). Comparing the
ratios in the radial with those in the cross-sections, they are
found to be nearly the same at fifteen twenty and twenty-five days,
but at the later ages those in the cross-sections are somewhat
larger than in the radial. It is difficult to determine whether
the ratios on the cross-section are really larger or whether the
GROWTH OF THE INNER EAR OF ALBINO RAT
105
result depends on the fact that the number of the cells here
measured is only one-fourth of that measured in the radial
section, and hence fewer cells of smaller size were included.
At any rate, these ganglion cells in both the radial and cross-
sections of the cochlea appear to grow at about the same rate.
The statistical constants for these cells and their nuclei are
given in tables 121 and 122.
Discussion
The nerve cells in the ganglion vestibulare are, as seen from
the above description, already well developed at birth both in
size and histological structure. After that time they grow con-
TABLE 120
Nucleus-plasma ratios of cells of the ganglion vestibulare, in cross-section
DIAMETERS COMPUTED M
BOOT
AGE
WEIGHT
Cell body
Nucleus
Nucleus-plasma
ratios
days
grams
15
20
23.9
12.0
1 :6.9
20
27
24.3
12.1
:7.1
25
39
24. ti
12.1
:7.4
100
95
25.6
12.3
:8.0
150
169
25.7
12.3
:8.1
371
220
26.0
12.3
:8.4
tinuously but slowly so long as followed. The increase from 1
to 546 days in the ratios of the diameters is in the cell body
1: 1.3, in the nucleus 1: 1.1, and is therefore very small. In the
cerebrospinal ganglion cells and in the cells of the cerebral
cortex, studied in the albino rat, there is no case which shows such
a small rate of increase between birth and maturity. The follow-
ing table 123 shows the ratios of increase which have been found.
It is to be noted that for the cells of the seventh spinal gang-
lion and the spinal cord, the ratios were taken from 17 to 360
days. If we had the ratios from 1 to 360 days, they would be
without question much larger.
There are a few measurements on the size of the ganglion
cells in the vestibular ganglion of various animals in the liter-
166
ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
ature. Schwalbe ('87) and Alexander ('99) report measurements
on these cells in several animals, but for the reasons already
given when considering the diameters of the cells in the ganglion
spirale, the values obtained by the authors are not repeated here.
TABLE 121
Giving the mean, standard deviation and coefficient of variability, with their re-
spective probable errors, for the diameters of the cells in the ganglion vestibulare,
in radial-vertical section
AGE
CELL
NUCLEUS
MEAN
STANDARD
DEVIATION
COEFFICIENT OF
VARIABILITY
days
1
Cell
20.1 0.16
1.46 0.11
7.3 0.55
Nucleus
11.7 0.11
0.99 0.07
8.5 0.64
3
Cell
22.6 0.14
1.33 0.10
5.9 0.44
Nucleus
11.9 0.07
0.63 0.05
5.3 0.40
6
Cell
22.8 0.13
1.23 0.09
5.4 0.41
Nucleus
11.9 0.05
0.43 0.03
3.6 0.27
9
Cell
23.6 0.16
1.48 0.11
6.3 0.48
Nucleus
12.0 0.0<9
0.82 0.06
6.8 0.52
12
Cell
23.6 0.14
1.28 0.10
5.4 0.41
Nucleus
12.0 0.06
. 59 . 04
4.9 0.37
15
Cell
23.6 0.13
1.21 0.09
5.1 0.39
Nucleus
12.1 0.06
0.60 0.05
5.0 0.38
20
Cell
23.9 0.16
1.54 0.11
6.5 0.49
Nucleus
11.9 0.10
0.90 0.07
7.6 0.55
25
Cell
24.2 0.16
1.48 0.11
6.1 0.46
Nucleus
12.1 0.08
0.74 0.06
6.1 0.46
50
Cell
24.1 0.30
2.80 0.21
11.6 0.88
Nucleus
11.8 0.09
0.86 0.06
7.3 0.55
100
Cell
24.3 0.20
1.86 0.14
7 . 7 . 58
Nucleus
12.2 0.09
0.86 0.06
7.0 0.53
150
Cell
24.1 0.18
1.70 0.13
7.1 0.53
Nucleus
12.2 0.09
0.83 0.06
6.8 0.52
260
Cell
24.3 0.26
2.45 0.18
10.1 0.76
Nucleus
11.9 0.07
0.67 0.05
5.6 0.42
367
Cell
25.2 0.22
2.07 0.16
8.2 0.62
Nucleus
12.3 0.09
0.88 0.07
7.2 0.54
546
Cell
25.0 0.19
1.80 0.14
7.2 0.54
Nucleus
12.1 0.09
0.81 0.06
6.7 0.50
On the differences between the growth of the cells in the ganglion
spirale and ganglion vestibulare. The foregoing discussion has
made plain that the vestibular ganglion cells grow not only in
size, but also in histological structure very much before birth,
while after birth they grow slowly though continuously. On the
other hand, the spiral ganglion cells are relatively immature at
GROWTH OF THE INNER EAR OF ALBINO RAT
167
birth, but in the earlier stages after birth grow very rapidly,
reach at twenty days their maximum size, and then diminish
slowly. This great difference in the course of growth is prob-
ably related to the maturity of the functions of the animal.
TABLE 122
Giving the mean, standard deviation and coefficient of variability with their respective
probable errors for the diameters of the cells in the ganglion
vestibulare on cross-section
AGE
days
CELL
NUCLEUS
MEAN
STANDARD
DEVIATION
COEFFICIENT OF
VARIABILITY
15
Cell
23.8 0.21
1.00 0.15
4.2 0.58
Nucleus
12.0 0.12
0.55 0.08
4.6 0.69
20
Cell
23.9 0.20
0.92 0.14
3.9 0.58
Nucleus
12.1 0.06
0.30 0.05
2.5 0.37
25
Cell
24.4 0.20
0.94 0.14
3.9 0.58
Nucleus
12.1 0.03
0.16 0.02
1.3 0.20
100
Cell
25.4 0.32
1.51 0.23
5.9 0.90
Nucleus
12.3 0.15
0.72 0.11
5.9 0.88
150
Cell
25.6 0.20
0.94 0.14
3.7 0.55
Nucleus
12.4 0.09
0.42 0.06
3.4 0.51
371
Cell
25.9 0.41
1.91 0.29
7.4 1.11
Nucleus
12.3 0.06
0.26 0.04
2.1 0.32
TABLE 123
Ratios of diameters between the ages given.
CEREBRAL CORTEX
DONALDSON AND
(SUGITA, '18)
NAOABAKA. '18
CELL
GROUP
LAMINA
LAMINA
OA88ERIAN
SPIRAL
VESTIBULAR
7TH
EFFERENT
PYHA-
GANO-
GANGLION
GANGLION
GANGLION
SPINAL
SPINAL
MIDIS
LIONARIS
NITTONO
WADA
WADA
GANGLION
CORD
C20)
CELLS
Age
days
1-730
1-730
1-330
1-546
1-546
17-360
17-360
Cell
body
1 :1.6
1 : 1.6
1 : 1.69
1 : 1.6
1 :1.2
1 :1.3
1 :1.2
Nucleus
: 1.5
: 1.5
: 1.20
: 1.2
: 1.0
: 1.2
: 1.2
As a consequence, in the nucleus-plasma ratio there is also
a large difference between the cells in the two ganglia. Table 124
shows this.
The ratio at birth in the ganglion vestibulare is large as com-
pared with that in the ganglion spirale, but the increase in this ratio
168 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
at 546 days is relatively slight as compared with what takes
place in the cells of the ganglion spirale. It appears, therefore,
that the cells in the vestibular ganglion are at birth in a more
mature condition.
As to the correlation between the development of the ganglion
cells and the equilibrium function, we have noted that the albino
rats, even just after birth, show some sense of equilibrium,
though the movements are lacking in coordination. With ad-
vancing age the balance of the body is held much better and all
the movements gradually become coordinated. The histological
structure and the size of the cells at birth suggest that they are
functional at that time, and the later increase in the volume
and maturity of the cells is accompanied by a corresponding
TABLE 124
GANGLION
VESTIBULARE
GANGLION
SPIRALE
Nucleus-plasma ratio at one day
Nucleus-plasma ratio at 546 days
1 :4.8
:7.9
1 : 1.3
:4.2
increase in the functional development. When the tactile sense
is well developed and the eyes open equilibrium is almost perfected.
It is a well-known fact that these two senses have very in-
timate relations to the maintenance of equilibrium. In this case,
as we might expect, the early development of a function is
accompanied by an early maturing of the neural mechanism
on which it depends.
Conclusions (for the ganglion vestibulare)
1. The measurements were taken on the largest nerve cells
of the ganglion vestibulare in the radial section of the cochlea,
and the developmental changes during portnatal growth studied
in fourteen age groups, comprising four ears in each group.
Further, in six age groups the cell size was determined in cross-
sections. The results have been given n tables 115 and 118
and charts 43 and 44.
GROWTH OF THE INNER EAR OF ALBINO RAT 169
2. The computed diameter at birth is 20.3 [x for the cell body
and 11.7 ^ for the nucleus, and at 546 days, 25.3 and 12.2 n,
respectively. Therefore the cells at birth are comparatively large
and increase in size very slowly, but the increase is continuous.
3. The increase in the ratio of the cell body is as 1 : 1.3, of the
nucleus as 1 : 1.1. We have between the same age limits no such
small rate of increase in any other cerebrospinal ganglion studied
in the albino rat. This small ratio indicates that the cells in
the vestibular ganglion are well developed at birth.
4. We find no appreciable difference in the diameters of the
cell bodies or the nuclei according either to sex or side.
5. Morphologically, the cells at birth are well differentiated.
The form of the cells is ovoid.
6. The nucleus-plasma ratios are large at birth and increase
regularly with age.
7. Comparing the development of the function of equilibrium
with the growth of the cells, we see that these are correlated.
Final summary
This study is concerned with the age changes in the organ
of Corti and the associated structures. The changes in the
largest nerve cells which constitute the spiral ganglion and the
vestibular ganglion, respectively, have also been followed from
birth to maturity. On pages 116 to 124 are given the summary
and discussion of the observations on the growth of the tympanic
wall of the ductus cochlearis.
The conclusions reached from the study of the largest nerve cells
in the ganglion spirale appear on pages 143 to 145. On pages
155 and 156 are presented the results of the study on the correlation
between the response to sound and to the conditions of the cochlea.
Finally, the observations on the growth of the largest cells in
the ganglion vestibu'are are summarized on pages 168 and 169.
It is not necessary to again state in detail the conclusions
reached in the various parts of this study.
At the same time, if we endeavor to obtain a very general
picture of the events and changes thus described, this may be
sketched as follows:
170 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
Within the membranous cochlea there occurs a wave of growth
passing from the axis to the periphery as shown in figures 4 to 13.
The crest or highest point of the tissue mass appears at birth
near the axis, in the greater epithelial ridge, and then progress-
ively shifts toward the periphery, so that at maturity it is in
the region of the Hensen cells. With advancing age the hair
cells come to lie more and more under the tectorial membrane
and the pillar cells seem to shift toward the axis.
At from 9 to 12 days the tunnel of Corti appears and the rat
can hear.
All of these changes occur first in the basal turn and progress
toward the apex. The mature relations are established at about
twenty days. There are thus two waves of change in the mem-
branous cochlea, from the axis to the periphery and the other
from the base to the apex. The rat can usually hear at twelve
days of age or about three days before the eyes open.
The largest cells in the ganglion spirale are very immature at
birth, reach their maximum at twenty days, and after that di-
minish in size, slightly but steadily. The rat hears, therefore,
before these cells have reached their full size.
The largest cells in the vestibular ganglion are precocious
and remarkably developed, even at birth. They cease their
rapid growth at about fifteen days of age, but increase very
slightly though steadily throughout life.
GROWTH OF THE INNER EAR OF ALBINO RAT 171
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SMALL, W. S. 1899 Notes on the psychic development of the young white
rat. Am. Jour. Psychol., vol. II.
174 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
SUGITA, N. 1918 Comparative studies on the growth of the cerebral cortex.
VI. On the increase in size and on the developmental changes of
some nerve cells in the cerebral cortex of the albino rat during the
growth of the brain. Jour. Comp. Neur., vol. 29.
TADOKORO, K., AND WATANABE, T. 1920 Experimental studies on the vital
fixations of the cochlea. Ikaijiho (Medical Review, Japan), no.
1345, p. 552.
VAN. DER STRICHT, O. 1918 The genesis and structure of the membrana
tectoria and the crista spiralis of the cochlea. Con. to Embryology
(Carnegie Inst. of Wash.), no. 227.
WATSON, J. B. 1907 Kinaesthetic and organic sensations: their rdle in the
reactions of the white rat to the maze. Psychol. Review, Monograph
Suppl., vol. 8.
WINIWARTER, A. v. 1870 Untersuchungen iiber die Gehorschnecke der
Saugetiere. Sitz. d. k. Akad. d. Wiss. in Wein, Bd. 61.
WITTMAACK, K. 1904 Ueber Markscheidendarstellung und den Nachweis
von Markhiillen der Ganglienzellen im Akustikus. Arch. f. Ohrenh.,
Bd. 61.
1906 Zur histo-pathologischen Untersuchung des Gehororgans mit
besonderer Berucksichtigung der Darstellung der Fett und Myelin-
Substanzen. Ztschr. f. Ohrenh., Bd. 51.
1907 Ueber Schadigungen des Gehors durch Schalleinwirkungen.
Verhandl. d. deutsch. otol. Gesellsch., Jena.
WITTMAACK, K., UND LAUROWITSCH, Z. 1912 Ueber artefizielle, postmortale
und agonale Beeinflussung der histologischen Bef unde im membranes
en Labyrinthe. Ztschr. f. Ohrenh., Bd. 65.
YOSHII, U. 1909 Experimentelle Untersuchungen iiber die Schadigung des
Gehororgans durch Schalleinwirkung. Ztschr. f Ohrenh., Bd. 58.

Revision as of 15:41, 18 September 2020

Wada T. Anatomical and physiological studies on the growth of the inner ear of the albino rat. (1923) Memoirs of the Wistar Institute of Anatomy and Biology, No. 10, Philadelphia.

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Donaldson H. The Rat - Reference tables and data for the albino rat (Mus norvegicus albinus) and the Norway rat (Mus norvegicus). (1915) Memoirs of the Wistar Institute of Anatomy and Biology, No. 6, Philadelphia.

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Anatomical And Physiological Studies On The Growth Of The Inner Ear Of The Albino Rat

Tokujiro Wada

Wistar Institute Of Anatomy And Biology


MEMOIRS

OF

THE WISTAR INSTITUTE OF ANATOMY AND BIOLOGY

No. 10


ANATOMICAL AND PHYSIOLOGICAL STUDIES

ON THE GROWTH OF THE INNER EAR

OF THE ALBINO RAT


TOKUJIRO WADA

THE WISTAR INSTITUTE OF ANATOMY AND BIOLOGY


PUBLISHED BY THE WISTAR INSTITUTE OF ANATOMY AND BIOLOGY

PHILADELPHIA


iflir


CONTENTS

Introduction 5

Material 6

Technique 6

I. On the growth of the cochlea 12

A. On the growth of the radial distance between the two spiral ligaments 13

B. On the growth of the tympanic wall of the ductus cochlearis. . . 16

1. Membrana tectoria 28

2. Membrana basilaris 39

3. The radial distance between the habenula perforata and the inner corner of the inner pillar cell at base 47

4. The radial distance between the habenula perforata and the outer corner of the inner pillar cell (resp., the inner corner of the outer pillar cell) at base 48

5. The radial basal breadth of the outer pillar cell (including the outer pillar) 57

6. The radial distance between the habenula perforata and

the outer border of the foot of the outer pillar cell 63

7. The greatest height of the greater epithelial ridge (dem grossen Epithelwulst Bottcher's s. Organon Kollikeri) resp.

of the inner supporting cells 63

8. The radial distance between the labium vestibulare and

the habenula perforata 68

9. The radial distance between the labium vestibulare and

the inner edge of the head of the inner pillar cell 71

10. Vertical distance from the membrana basilaris to the summit of the pillar cells 75

11. The greatest height of the tunnel of Corti 77

12. The height of the papilla spiralis at the third series of the outer hair cells 77

13. The greatest height of Hensen's supporting cells 83

14. The angle subtended b> the extension of the surface of the lamina reticularis with the extended plane of the membrana basilaris 84

15. Lengths of the inner and outer pillar cells 85

16. Inner and outer hair cells 94

17. Deiter's cells 109

18. Summary and discussion 116

C. On the growth of the largest nerve cells in the ganglion spirale . 124

observations 124

Discussion 136

Conclusions . ... 143


3 (,


4 CONTEN TS

II. Correlation between the inception of hearing and the growth of the

cochlea 145

Observation 146

Discussion 152

Conclusions 155

III. On the growth of the largest nerve cells in the ganglion vestibulare. . . 156

Material and technique 156

Observations 156

Discussion 165

Conclusions 168

Final summary 169

Literature cited . . . 171


ANATOMICAL AND PHYSIOLOGICAL STUDIES

ON THE GROWTH OF THE INNER EAR OF

THE ALBINO RAT

INTRODUCTION

Since Alphonse Corti, in 1851, published his famous work on the cochlea of mammals, studies on this organ have been made by many authors and have produced fairly concordant results. Concerning the postnatal growth of the internal ear, however, systematic studies are lacking. Especially is there no investi- gation, so far as I know, on the growth of the nerve cells in the ganglion spiral, not even in the great work of Retzius. ('84).

It was the special object of these studies, therefore, to follow the growth of the cells forming the spiral ganglion from birth to maturity and to correlate the changes in them with the ap- pearance of the functional responses and with the structural changes in the membranous cochlea. In the course of this in- vestigation studies were made also on the cells of the ganglion vestibulare, in order to see whether these cells differed in their growth from the cells in the spiral ganglion. Both of these ganglia are situated in the course of nervus acusticus, but have, as is well known, entirely different functions.

Thus determinations have been made on the diameters of the cells of the ganglion spirale and of their nuclei at different ages; of the nucleus-plasma ratios and of then* growth in relation to those of other portions of the membranous cochlea. For the cells of the vestibular ganglion similar determinations were also made. Finally, these results have been compared with those obtained from the study of other craniospinal ganglia in the albino rat.

In presenting my results I shall begin with a description of the changes in the larger portions of the membranous cochlea and pass from these to the cell elements themselves, and then to the observations on the ganglion cells and to the correlation between hearing and the growth of the cochlea.


6 * ANATOMICAL AND PHYSIOLOGICAL STUDIES ON

MATERIAL

For the present studies forty male and thirty female albino rats were used, representing every phase of postnatal growth and having approximately standard body weights. These were all from the colony of The Wistar Institute, and were sometimes from the same, and sometimes from different litters.

At first all these rats were tested for their ability to hear and their equilibrium, and it was ascertained that after about twelve days of age, or somewhat earlier, they responded posi- tively to the test for hearing. Such examinations were deemed necessary, to make certain that the rats used were normal.

I have arranged the animals thus tested in fourteen groups according to age, each group having five individuals in it. Serial sections from all these cochleas were made by methods to be given later. Most of them were in the plane of the vertical axis of the cochlea, but some were at right angles to it.

From the former I selected four ears in each group for the study of the growth of the cochlea. For the study of the growth of the ganglion vestibulare, I have used for the most part the same specimens. For the study of the sections at right angles to the vertical axis of the cochlea, sections from one ear of each group were used.

TECHNIQUE

In order to obtain good preparations of this delicate organ, the method of vital fixation (injection under anaesthesia) was used. The method employed, and which proved almost ideal, was that introduced by Metzner and Yoshii ('09), Siebenmann and Yoshii ('08) and somewhat improved by Sato ('17). After the animals had been tested to make sure that they were quite normal, the fixing solution was injected through the aorta under ether. The brain was then carefully removed, care being taken not to drag the trunk of the nervus acusticus, as noted by Nager ('05), and the bulla tympanica was opened to allow the further penetration of the fluid.


The bony labyrinth with its surrounding bones was then placed in the fixing solution for two weeks, the fluid being re- newed every day.

The fixing solution which I used consists, according to Yoshii ('09), of

10 per cent formol 74 parts

M tiller's fluid 24 parts

Glacial acetic acid 2 parts

According to Tadokoro and Watanabe ('20), this solution is one of the best, ranking with that of Wittmaack ( '04, '06) and that of Nakamura ('14).

This injection method is sometimes difficult to apply to very young rats on account of the small size and the delicacy of the vessels. When injection failed in very young animals, then immediately the head was cut off and put directly in the fixing fluid. Owing to the incomplete calcification of the very young cochlea, the fixing solution enters rapidly and fixes the deep- seated organs in good condition. Since the parts of the internal ear are not yet well developed in the very young rats, they do not suffer from this method of fixation as do the older cochleas.

Indeed, no differences are to be seen between the sections prepared by vital fixation and by decapitation in very young rats.

For decalcification I have employed the following solution during three days, renewing it every day.

Decalcifying fluid

5 per cent aqueous nitric acid 49 parts

10 per cent formol 49 parts

Glacial acetic acid 2 parts

After the specimens had been washed in running water for three days, they were passed through the alcohols from 50 to 97 per cent. For the imbedding I have used 'parlodion' with good results. Here it is to be mentioned that all the cochleas were treated in the same way, even unossified cochlea being passed through the decalcifying fluid, so that there should be absolutely no differences in treatment.


8 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON

The next important matter is the determination of the plane of the section. For the measurement of growth changes it was necessary to obtain corresponding sections from the several cochleas. In an organ like that of Corti, which changes in its details from one end to the other, however, it is very difficult to accomplish this, but I believe that I have overcome most of the difficulties.

After much testing, I found that a section parallel to the under surface of os occipitale in the fronto-occipital direction runs nearly exactly parallel to the axis of the modiolus of the cochlea. In order to get the same direction from right to left, I have taken as the standard the transverse plane of the under surface of the os occipitale, controlling the direction of the section with a magnifying glass. Thus nearly the same radial direction and nearly corresponding places in the cochlea were obtained in the several series of sections. This makes possible a trust- worthy comparison of the measurements and drawings.

The cross-section of the cochlea was gotten by making the plane of the cut transverse to the axis of the modiolus. To get the corresponding levels is difficult. At first I divided all the serial sections by 2^, which is the number of complete turns in the cochlea of the albino rat. Next, from the number of the slides representing each turn, I determined nearly the corres- ponding level in the cochlea according to age.

All the sections were 10;x in thickness. The sections were stained for the most part with haematoxylin and eosin, but sometimes by Heidenhain's iron haematoxylin or the iron hae- matoxylin and Van Gieson's stain. For the measurements, however, only the sections stained with haematoxylin and eosin were used.

For the examination of the larger parts of the cochlea and their relations, the sections were projected on a sheet of paper by the Leitz-Edinger projection apparatus, at a magnification of exactly a hundred diameters, and the outline of the image accurately traced. The remaining measurements of the ganglion cells and the smaller portions of the cochlea were made directly under the microscope. The measurements made on the tympanic


GROWTH OF THE INNER EAR OF ALBINO RAT 9

wall of the cochlea are somewhat complicated, but by the aid of figures 1 and 2 they may be explained. In figure 1 lines 1-1, 1-1'. 2-2, 3-3 indicate, respectively, the height of the arch of Corti, of the tunnel of Corti, of the papilla spiralis (Huschke) at the third series of outer hair cells, and of Hensen's supporting cells, respectively, above the plane of the membrana basilaris.

Lines 4-4' which are the extensions of the surface of the lamina reticularis and of the membrana basilaris, subtend the angle 8.

To get the exact measurements of the radial breadth of the membrana tectoria is very difficult, if not impossible, because it is sinuous in its course; moreover, it differs in thickness from point to point. Therefore, it has been variously described by different authors. Intra vitam fixation tends to prevent dis- tortion. We divide the membrana tectoria, figure 1, into two portions, the first or inner (7-7'-9-9') and the second or outer (5-5 '-7-7') or outer zones of Retzius; each of these is again divided in two at 6-6' and 8-8', as shown in figure 1.

I have measured the radial distance of each portion and added all four together. This total approximates the natural radial breadth of this membrane, and since the sections have all been prepared in the same way and examined by the same method, the relations during growth can be followed.

In figure 2, 1-1 and 2-2, mark the length of the inner and outer pillar cells, respectively, from base to the point, which is situated just under their junction. It is to be noted here that the term ' pillar cell ' here applies to the pillars in the strict sense and does not include the associated cells.

Distances 3 and 7 in figure 2 show the basal breadth of the inner and outer pillars, respectively. The former is identical with the distance between the habenula perforata and the outer corner of the inner pillar after the inner corner of the pillar has reached the habenula perforata, but there is some difference between the two distances in very young rats. Distance 4 is that between the habenula perforata and the inner corner of the outer pillar; distance 5 is that between the habenula per- forata and the outer corner of the outer pillar. The latter rep- resents at the same time the radial breadth of the zona arcuata of the membrana basilaris.


10 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


Fig. 1 Showing the localities for the measurement of each part of the tym- panic wall of ductus cochlearis in the albino rat, 100 days old radial vertical section. 1-1, height from the basal plane to the surface of pillar cells; 1-1', greatest height of the tunnel of Corti; 2-2, height of papilla spiralis at the third series of the outer hair cells; 3-3, height of Hensen's supporting cells; 4~4', 4 indicates the extension of the membrana basilaris and 4' the extension of the lamina reticularis. The two lines subtend the angle 0. The radial breadth of the membrana tectoria is taken as the sum of the four segments between the lines 5-5' and 9-9'.

Fig. 2 Showing the method of measurement for several parts of the tym- panic wall of the ductus cochlearis in the albino rat, 100 days old. 1-1, length of inner pillar cell without head; 2-2, length of outer pillar cell without head Distance 3 shows radial distance between habenula perforata and the outer corner of inner pillar at base after twelve days of age this equals the radial basal breadth of inner pillar. Distance 4, radial distance between habenula per- forata and the inner corner of outer pillar at base. Distance 5, radial breadth of the zona arcuata (Deiters') of membrana basilaris, and at the same time it indicates radial distance between habenula perforata and the outer corner of outer pillar at base. Distance 6, radial distance between the outer corner of inner pillar and the inner corner of outer pillar at base. Distance 7, radial basal breadth of outer pillar. Distance 8, radial distance between the habenula perforata and outer corner of inner pillar cell at base. Distance 9, radial basal breadth of the outer pillar cell. Distance 10, radial breadth of zona pectinata of the membrana basilaris. Distance 11, radial breadth of entire membrana basilaris.

Fig. 3 Showing the general outline of the cochlea in the radial vertical section albino rat, 100 days of age.

ABBREVIATIONS

Line 1, 1, distance between two basal L.L.S., limbus laminae spiralis

spiral ligaments L.S., ligamentum spirale

Line 2, 2, distance between two apical L.S.O., lamina spiralis ossea

spiral ligaments M.T., membrana tectoria

7, first turn N.C., nervus cochlearis

II, second turn O., bone

///, third turn P.S., papilla spiralis

IV, fourth turn S., stria vascularis

D.C., ductus cochlearis S.T., scala tympani

G.S., ganglion spirale S.V., scala vestibuli G.V., ganglion vestibulare


GROWTH OF THE INNER EAR OF ALBINO RAT


11



12 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON

Distance 6 is that between the outer corner of the inner pillar and the inner corner of the outer pillar. Distance 8 is that between the habenula perforata and the outer corner of the inner pillar cell. Distance 9 shows the radial basal breadth of the outer pillar cell plus the outer pillar. Distance 11 shows the radial breadth of the membrane basilaris comprising distance 5 (zona arcuata) and 10, which is the radial breadth of the zona pectinata of the membrana basilaris.

ON THE GROWTH OF THE COCHLEA

As noted above, I have selected from at least seven serially sectioned cochleas in each age group, four for this study, taking one section in good condition from each labyrinth. From these four sections the average values were taken for each age. Table 1 gives the data for the rats used here. As we see, sometimes two, sometimes three animals were used at each age to get the four best-prepared sections which corresponded. Determinations accordingly to sex and side, therefore, cannot be based on like numbers.

In the following text we shall often refer to the I, II, III and IV turns of the cochlea. This calls for a word of explanation. As the cochlea of the rat has nearly 2^ complete turns, four cochlear canals are usually obtained in the radial vertical sections, as prepared by me (fig. 3). Therefore, turn I does not mean the first complete turn, but about the middle part of the basal turn; turn II about the beginning of the middle turn; turn III about the middle part of the middle turn, and turn IV about the beginning of the apical turn of the cochlea. Usually the cochlea has been divided for description by the authors into the first, second, and third turns, or more definitely into the basal, middle, and apical turns. For the purpose of this study, however, it is desirable to adopt the divisions given above, because here measurements are largely employed, and there are some differ- ences in size, volume, and arrangement of structures, even between the beginning and end of the same turn.

At all events, it is to be kept in mind that such divisions are arbitrary, as the changes in the elements take place in a graded manner.


GROWTH OF THE INNER EAR OF ALBINO RAT 13

A. On the growth of the radial distance between the two spiral ligaments (fig. 3, 1-1, 2-2)

As we have usually four sections of the ductus cochlearis, therefore four spiral ligaments in one radial vertical section, there are two radial distances presented, the first, figure 3, 1-1, connecting the two basal sections of the ductus on opposite sides, and the second, figure 3, 2-2, connecting the two apical


TABLE 1 Data on the albino rats used for the study of the cochlea


AGE


BODY WEIGHT


BOOT LENGTH


BEX


SIDE


HEARING


days


grams


mm.





1


5.3


48


d"


R. L.



1


4.2


47


o"


R. L.



3


8.8


60


a"


R.



3


7.1


54


o"


R. L.



3


8.2


56


9


R.



6


10.2


64


9


R. L.



6


11.0


62


tf


R. L.



9


9.1


58


9


R. L.



9


9.8


57


tf


R. L.


=fc


12


13.0


70


a 1


L.


+


12


11.9


68


9


R. L.


+


12


14.8


72


d"


L.


+


15


13.0


74


0"


R.


+


15


13.5


75


9


R.


+


15


13.0


74


9


R. L.


+


20


30.0


96


cf


R. L.


+


20


28.0


94


c?


R. L.


+


25


38.4


107


9


R. L.


+


25


34.2


101


9


R. L.


+


50


60.0


128


9


R. L.


+


50


57.5


121


9


R. L.


+


100


145.6


176


a 1


L.


+


100


102.5


154


9


R.


+


100


100.5


152


9


R. L.


+


150


153.5


184


9


R.


+


150


188.9


191


d 1


R. L.


+


150


198.8


192


<?


R.


+


250


133.5


178


9


R. L.


+


263


140.3


171


9


R. L.


+


365


205.4


202


0"


L.


+


365


170.4


182


9


R. L.


+


368


179.0


196


9


R.


+


546


282.1


222


<?


R. L.


+


546


227.1


204


rf


R. L.


+


14


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


sections. These distances measure the radial breadth of the

membranous cochlea and of the modiolus combined at these levels.

In table 2 (chart 1) are entered the values for the radial

distances found between the two spiral ligaments in fourteen

TABLE 2

Radial distance between the two spiral ligaments in radial-vertical section (chart 1, figure 3)




AVERAGE DISTANCE BETWEEN TURNS IN M


AGE


TTTT'nWP





I-II


III-IV


I-II plus III-IV


days


grams




mean


1


5


1410


925


1168


3


8


1560


1025


1S93


6


11


1650


1175


1413


9


10


1635


1225


1430


12


13


1640


1233


1437


15


13


1655


1235


1445


20


29


1645


1250


1448


25


36


1620


1250


1435


50


59


1615


1253


1434


100


112


1663


1270


1467


150


183


1618


1290


1454


257


137


1655


1275


1465


366


181


1635


1285


1460


546


255


1680


1265


1473


Ratios 1 12 days 1 1.2


1 20 " 1.2


1 546 " 1.3


TABLE 3 Condensed

Ratios of distances between the two spiral ligaments along 1-1 (turns I-II) and along 2-2 (turns III-IV), figure 3


AGE


BODY WEIGHT


Ratios between the two distances turns I-II and III-IV


days


grams



1


5


. 1:0.66


8


11


0.72


18


21


0.75


213


138


0.77


age groups, from one to 546 days. As we see, the average value of the two distances grows rapidly from birth till six days of age. After that period the value increases gradually till twenty days, while after twenty days the increase is very slight indeed. The ratios between 1 and 12, 1 and 20, and 1 and 546 days show these relations.


GROWTH OF THE INNER EAR OF ALBINO RAT


15


In table 3 are given the average ratios between two radial distances between I-II and III-IV at four ages. Here we can also see a rapid increase in the ratio from one to eight days of age, while afterwards the ratios rise very gradually. The data in table 2 show that at nine days the mean diameter of the bony cochlea as thus measured is approximately 97 per cent of the value at maturity. The cochlea thus attains nearly its full size at an early age. Chart 1 illustrates this point.


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Chart 1 The radial distance between the spiral ligaments, turns I-II and III-IV, table 2, figure 3 (/-/) and (-).

Radial distance at turns I-II.

Radial distance at turns III-IV.

Average radial distance for the two foregoing measurements.

All the charts are plotted on age.

The scale for age changes at 50 days. From to 50 days one interval is equal to five days. From 50 days on, one interval is equal to twenty-five days.

Unless otherwise stated, the measurements recorded in these charts have been made on radial-vertical sections.


16 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON

B. On the growth of the tympanic wall of the ductus cochkaris

Figures 4 to 12 show the appearance in outline at birth, at three six, nine (not hearing), nine (hearing), twelve, twenty one hundred, and 546 days, respectively. These figures have been drawn from the best corresponding sections at the beginning of the middle turn of the cochlea, figure 3, turn n, which I have selected as the type, as did Retzius.

The fact, demonstrated by many authors, Bottcher ('69), Retzius ('84), and others, that development progresses from the basal to the apical turn is confirmed in the albino rat.

In the albino rat the development of the cochlea, and es- pecially of the ductus cochlearis, is somewhat retarded as compared with man, and the papilla with its elements developed in a great measure during the first ten days after birth.

As we see in figure 4, the ductus cochlearis in the new-born rat is very immature. It is remarkable that the space which lies in adult rats axialward of the papilla spiralis between the membrana tectoria and the limbus spiralis-sulcus spiralis internus (fig. 10) is not yet to be seen. Instead of the space, there is the so- called greater epithelial ridge (der grosse Epithelwulst of Bottcher) figure 4, G. consisting of pseudostratified epithelial cells. These long and narrow cells lie pressed very closely together with their large oval nuclei at various heights. The surface of the prominence sinks slightly in its center, and at the outer end of the prominence more rapidly, where it passes over into the so- called lesser epithelial ridge fig. 4, L. (der kleine Epithelwulst) at an obtuse angle.

The latter is, of course, a relatively small prominence, making up the greater part of the papilla spiralis. The pillar cells of Corti lie with their upper ends at the most inner part of the surface of the lesser ridge just in the angle with the greater ridge. They form two entirely separate rows of cells, the inner and the outer, but so close together that we cannot detect any space between them. Only the protoplasm of the inner pillar cell is more transparent above the nucleus, and on the inward side there is a thin rod passing from the upper end to the lower


GROWTH OF THE INNER EAR OF ALBINO RAT 17

part near the base. This transparent area is not the locus of the future tunnel of Corti, but marks the protoplasmic change into the pillar, as the transparent substance condenses into the rod. We can see this change beginning in the basal turn before it appears in the apical turn of the cochlea. The inner and outer cells make a triangle with a narrow base, which clings to the membranea basilaris; they turn somewhat outward. 1

A large oval nucleus lies in the basal part of each cell; that of the inner pillar cell is very large, about twice as large as that of the outer, and with its long axis in a radial direction. As figure 4 shows, the inner corner of the inner pillar cell does not yet reach to the habenula perforata.

The hair cells, which in the albino rat are in four rows through all the turns, are separated by the pillar cells into two groups, the inner containing one and the outer three rows of cells. They are comparatively well developed at birth (fig. 4). The inner hair cell belongs to the greater ridge, as Kolliker ('67), Gottstein (72), Retzius ('84), Held ('09), and others have already affirmed, and contrary to the assertaion of Bottcher ('69) and others.

It is situated in the most outer part of the declivity of the greater ridge and slants away from the axis with its round lower end at about half the height of the greater thickening. It has a large round nucleus in the base and the small hairlet at the top. This hair cell is nearly twice as large as the outer hair cells. The three outer hair cells reach down to the middle of the lesser ridge, not through it, having no process at their basal end. They end with their upper parts at the surface of the prominence. They stand not straight, but turn with their long axis very slightly inward, i.e., the in direction opposite to the long axis of the inner hair cells. They are cylindrical in form with a round nucleus at their base and small hairlet on the top.

Below the outer hair cells stand the three rows of Deiters' cells, which have large oval nuclei. These rest with their wide bases on the basilar membrane and their pointed ends reach to the surface of the epithelium. They are retarded in develop-

1 In the following description of the cochlea, 'outward' means away from the axis 'inward' towards the axis.


J8 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON

ment, and at birth their cell bodies are short and undeveloped, so that they hardly suggest the adult cells.

Hensen's supporting cells (fig. 10, at maturity) are as yet undeveloped and nearly uniform in height, their nuclei being at nearly the same level.

Outward from the Hensen's cells the height of the epithelial cells at maturity rapidly diminishes and passes over to the cylindrical cells of sulcus spiralis externus. At birth no such distinction is present. Through all the turns the surface of the lesser epithelial ridge remains about parallel to the plane of the membrana basilaris.

The membrana basilaris, which stretches from the labium tympanicum outward to the crista basilaris of the ligamentum


Figs. 4 to 12 Showing the increase in size and morphological changes in each part of the tympanic wall of ductus cochlearis of the cochlea during growth, in the radial vertical section albino rat. All the figures have been uniformly enlarged.

Fig. 4 One day. C, greater epithelial ridge; L, lesser epithelial ridge.

Fig. 5 Three days.

Fig. 6 Six days.

Figs. 7 to 8 Showing the differences in size and morphological changes in the tympanic wall of ductus cochlearis between a nine-day-old rat which can already hear (fig. 8) and one that cannot (fig. 7)

Fig. 9 Twelve days.

Fig. 10 Twenty days. In figure 10 we have drawn all the elements of the organ.

ABBREVIATIONS

M.T., membraua tectoria a. Corti O.P., outer pillar

L.V., labium vestibulare of crista B.C., basal cells

spiralis D.C., Deiters' cells

S.S.I., sulcus spiralis interims Bo.C., Boettcher's cells

S.I.C., cells of sulcus spiralis interims L.S., ligamentum spirale

I.S., inner supporting cells N.F., myelinated fibers of ramus I.H., inner hair cells acustici

O.H., outer hair cells R.F., radial fibers of ramus basilaris H.S., Hensen's supporting cells acustici in the tunnel of Corti

S.E.C., cells of sulcus spiralis externus T., tunnel of Corti

M.B., membrana basilaris B., blood vessels

I. P., inner pillar 0., bone

Fig. 1 1 One hundred days.

Fig. 12 546 days.


GROWTH OF THE INNER EAR OF ALBINO RAT 19

4



20


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON



GROWTH OF THE INNER EAR OF ALBINO RAT


21


HS



22

spirale, consists of two layers, an upper, membrana basilaris propria, and an under, tympanic investing layer (tympanale Belegschicht : Retzius). The former, of course, is divided into two portions, an inner, zona arcuata (Deiters) and an outer, zona pectinata (Todd-Bowman). While the zona arcuata is thin from the beginning of life, the zona pectinata thickens at its central part where it contains cells with oblong nuclei. On passing to the spiral ligament it again becomes thin. In the young, the under layer is not so regular in structure as in the adult. The *cells close to the basilaris propria are arranged vertically.

On the contrary the cells below them, which vanish in great part with age, have an irregular arrangement; those near the endothelial cells of scala tympani having a more radial arrange- ment. Therefore, this layer is thick, several times the thickness of the basilaris propria, and the thickness increases towards the upper turns. The vas spirale is strikingly large at this stage and lies just under the outer pillar and the Dieters' cells.

The membrana tectoria, beginning at the inner angle of the ductus cochlearis, where Reissner's membrane rises, covers the epithelium of the limbus laminae spiralis and the greater epithelial ridge, lying close to their surfaces. At the inner part it is thin, but thickens where the greater ridge begins, and at the outer part again becomes thin. In the basal turn there is seen as a very thin strand reaching to Hensen's prominence, but in the apical turn it reaches hardly to the inner hair cell. Although it gives rise to several thread-like processes going to the surface of the papilla, these do not seem to connect with the hairs of the hair cells, but with the terminal plates of the Dieters' cells.

When we divide the tympanic wall of the ductus cochlearis at the boundary between the greater and lesser epithelial ridges, we observe that the inner portion from the inner angle to the outer end of the greater ridge is far larger than the outer portion, which, however, is the more important for hearing. This relation becomes more evident as we pass from the base to the apex. Moreover, the total radial length of the tympanic wall


GROWTH OF THE INNER EAR OF ALBINO RAT 23

diminishes at this stage towards the apex, though it is larger in the beginning of the middle turn than in the middle of the basal turn. As will be shown later, these relations are entirely reversed in the adult cochlea. This fact indicates that the cochlea at this stage is very immature.

In the three-day-old rat the cochlea is much better developed (fig. 5). The radial breadth of the typmanic wall of the ductus cochlearis becomes greater in all the turns, especially in the upper turn; therefore the differences between the radial breadths in each successive turn are smaller than at the earlier stage. There is some change as we pass towards the apex in the relation of the inner and outer portion of the tympanic wall. At the basal turn and the beginning of the middle turn the radial breadth of the outer portion increases greatly, but diminishes again towards the apex. Although the radial breadth of the inner portion increases through all the turns, the proportion of this increase becomes greater towards the apex. As the inner portion is composed of the greater epithelial ridge and of the limbus laminae spiralis, and as the breadth of the latter diminishes towards the apex, the increase of the radial breadth of the inner portion is due to changes in the greater epithelial ridge.

The heights of the greater epithelial ridge, however, diminishes through the successive turns, becoming less and less from base to apex. Thus in the cochlea at this age it has a small radial breadth and vertical height in the basal turn and a larger radial breadth and height in the upper turns.

In all the turns the inner hair cell is inclined outwards and lies with its surface forming the outermost part of the greater ridge. The obtuse angle which it helps to make (fig. 5) as a boundary between the greater and lesser ridge in upper turns, vanishes in the basal turn where there is no sharp boundary between the two ridges.

The pillar cells of Corti develop more and more during this early stage; the radial breadth of their base increases, but as yet there is no space between them. They incline much more outwards than in the earlier stage. The protoplasmic change in the rod progresses, especially in the basal turn, and the head plate of the cell can be seen distinctly.


24 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON

The outer hair cells become higher and wider; they are slightly inclined inward in the upper turn. On passing towards the basal turn the inclination inward increases, and in the basal turn it is most oblique, almost at 45, to the plane of the basilar membrane. In figure 4 the inclination of these cells is only slight.

Deiters' and Hensen's cells are not well developed; the con- ditions are as in the former stage.

The plane of the surface of the lesser epithelial ridge is inti- mately related to the development of the outer hair cells and Deiters' cells, and as the latter are in an undeveloped condition, it runs nearly parallel to the plane of the membrana basilaris, sometimes dipping outward.

The membrana basilaris seems to be much longer; its com- position is about the same as that in the one-day rat, only the thickness is somewhat decreased, owing to the reduction of the rows of cells in the tympanic layer.

The membrana tectoria grows in breadth and thickness, covering very closely the inner portion of the tympanic wall and connects outwards with Deiters' and Hensen's cells by slender fibrous processes the so-called outer marginal zone. The hairs of the cells stand between these processes, but have no connection with them.

The vas spirale does not suffer reduction.

At six days (fig. 6) the development of the cochlea has pro- ceeded futher. The radial breadth of the tympanic wall has increased. Thus we find the tympanic wall, especially its inner portion, increasing towards the apex, chiefly owing to the aug- mentation of the radial breadth of the greater ridge. In this a remarkable change is to be seen. In the basal turn the long slender cells disappear in the inner part of the greater ridge, and instead of them there are found cylindrical cells with oval nuclei near their bases.

The height of these cells increases gradually to the level of the surface of the inner hah- cell; their upper surface is here in contact with the membrana tectoria. Thus a space appears between the cylindrical epithelium and the membrane the sulcus


GROWTH OF THE INNER EAR OF ALBINO RAT 25

spiralis interims which is deep and wide in the basal turn, becomes gradually shallow and narrow as we pass upward, and in the middle part of the middle turn is to be seen as a small and flat space. In the apical turn it is not yet present. The inner side of this space is made by the labium vestibulare of the limbus laminae spiralis.

As a result of this change in the greater ridge, the obtuse angle between the greater and lesser ridge vanishes entirely, and the two surfaces come to lie in the same place. The inner hair cell becomes larger and inclines less outward.

It is to be noted that the inner hair cell is supported on both sides by long slender cells. These have been variously described by several authors, but first Hans Held ('02) and afterwards Kolmer ('07) have considered them as supporting cells, reaching from the surface of the hair cell to the plane of the basilar membrane. Held has termed the cell which lies outward the ' Phalangenzelle. '

I have paid some attention to this cell and the changes in it. It is long and slender and stands between the inner hair cell and the inner pillar cell, with the upper end reaching to the surface, and is attached at its base to the inner corner of the inner pillar. The oblong oval nucleus lies in its basal portion. On the inner side of the inner hair cell there is a group of two to three cells of the same kind. These cells, termed ' Grenzzellen ' by Held, stand near the habenula perforata, reach to the height of epithelium, and have their bases in intimate relation to the former.

These are not neuro-epithelial cells nor in intimate relation with the nerve fibers, but similar to the Deiters' cells which support the outer hair cells.

The developing pillar cells become progressively wider at their bases. The inner pillar cell sends a long foot towards the habenula perforata and in the basal turn it sometines reaches to it. The outer pillar cell increases its length very rapidly and extends its foot outward on the basilar membrane. Thus in the basal turn the triangle made by the inner and outer pillar cells and having a short base, in the upper turns changes to an equilateral


26 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON

triangle and stands upright on the basilar membrane. In the apical turn the inner pillar cell is not yet so long as in the lower, turns and is still inclined outwards. The head plates and pillars are fairly prominent, but there is as yet no space between them.

The outer hair cells have grown and are inclined inward. Deiters' and Hensen's cells have not yet begun to develop, as have the other elements of the organ of Corti just described.

In the membrana basilaris we see the reduction of cells in the tympanic covering layer. The vas spirale shows more or less reduction. The membrana tectoria increases its radial breadth following the associated structures. The so-called marginal zone connects with Hensen's cells and the lamina reticularis by fibrous processes.

Among five nine-day-old rats, as shown later, one responded to the tests for hearing. As the majority of them gave no re- action, the cochlea of the latter, non-hearing rat, may be taken as the type for this age. The differences between the cochlea of the hearing and non-hearing rats will be mentioned later.

In rats of this age (fig. 7.) the cochlea is still further advanced. The sulcus spiralis internus appears through all the coils, and is deepest and broadest in the basal turn, diminishing in depth or gradually toward the apex. The cells covering the space are low and cuboid in the lower turns, but in the apical turn they are yet relatively high, cylindrical cells.

These cells probably have their origin from the long slender cells of the greater epithelial ridge, as Bottcher ('69) and others maintain, although Gottstein (72) and some others think that they come by the outward migration of the epithelium of the limbus spiralis, and Retzius ('84) regards this latter view as the more probable.

The inner and outer hair cells become large and approach their mature form. The supporting cells of the inner hair cell are very evident.

The pillar cells develop more and more, their radial breadth increases and the pillars and headplates also become distinct. Sometimes we see a small space between the inner and outer pillar cells in the lower turn, but not in the upper. Nuel 's space


GROWTH OF THE INNER EAR OF ALBINO EAT 27

is not yet to be seen. Deiters' cells become longer, somewhat in the processus phalangeus but chiefly in the cell body, and the nuclei move upward. Hensen's cells also increase in height slightly.

While the membrana tectoria lies close to the surface of the outer part of the greater ridge in the upper turns of the cochlea, there arises a small space between them, which is continuous with the sulcus spiralis internus. The outer marginal zone of the membrane is still connected with Hensen's supporting cells and the lamina reticularis. The vas spirale remains as a large vessel. This is the condition of the nine-day cochlea in a rat which does not hear.

Although the detailed description of the cochlea of the nine- day rat which can hear will be deferred for a time, yet to complete the series of growth changes, figure 8, representing the cochlea in such a rat, is inserted here.

In the next stage, twelve days old (fig. 9), the development of the tympanic wall is much advanced. The cells lining the sulcus spiralis internus and the-inner supporting cells have nearly their mature form and arrangement in the basal and middle turns; only in the apical turn many and slender cells remain close to the inner hair cell.

The outer pillar cell shows a remarkable increase in length so that it is twice as long as in the former stage, while the growth of the inner pillar is much less marked.

Therefore the outer pillar is much longer than the inner through all the turns. From this change in the pillar cells it results that the nearly equilateral triangle formed by them becomes unequal and its summit is shifted inward. In all the turns we can see the tunnel of Corti and also the space of Nuel. The hair cells develop further and their previous inclinations are increased.

Deiters' cells show a very rapid development, especially in the cell body, which increases many times, the nucleus moving upwards. The inclination of these cells follows that of the outer hair cells.


28 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON

Hensen's supporting cells are also fully developed. Through the development of Deiters' and Hensen's cells a change is effected in the course of the lamina reticularis. It runs no longer parallel to the plane of the membrana basilaris, but dips inward.

Though the membrana basilaris remains nearly stationary in its breadth, the thickness of the tympanic covering layer is reduced and the longitudinal nuclei in the zona pectinata diminish in number.

The membrana tectoria reaches in the basal turn to the outer- most row of the outer hair cells, but the apical turn only to the second row. The so-called 'outer marginal zone' connects with the terminal frame (Schlussrahmen) of the lamina reticularis.

In the next stage, the twenty-day-old rat (fig. 10), the papilla spiralis and the tissues about it are developed almost com- pletely; therefore, the structural relations of the cochlea accord nearly with those of the adult cochlea, as generally recognized in histology.

It is to be noted here that in the basal turn, Bottcher's cells are to be seen in sulcus spiralis externus* as a cell group situated on the outer part of the vestibular surface of the membrana basilaris. This cell group consists of several granular compact and sharply bounded cells entirely covered by high swollen cells on all sides. That this cell group belongs to the epithelium of the sulcus spiralis externus can be easily demonstrated. While the cells in this group show no particular changes in structure, the neighboring cells diminish in their height and size towards the apex, and finally become similar to the former. After twenty days of age the general features of the cochlea are those of the adult and do not require general description. The finer differ- ences will be discussed in subsequent chapters.

Figure 11 shows the relations at 100 days and figure 12 at 546 days.

1. Membrana tectoria. As stated above, this membrane is divided into two zones, an outer and inner, using the outer edge of the labium vestibulare as the point of division (fig. 1, 7-7'). Each zone was again divided into two equal parts at 6-6'and8-8'. Thus the sum of the breadths of the two outer parts represents


GROWTH OF THE INNER EAR OP ALBINO RAT 29

in each instance the breadth of the outer zone, and the sum of the two inner parts that of the inner zone, while the sum of all four parts gives the total radial breadth. For the purpose of the exact measurement of the growth of the membrane, I have, as noted above, projected the sections at 100 diameters and made the determinations on the outlines thus obtained.

In table 4 (charts 2 and 3) are given the values for the total average breadth, as well as for that of each zone, and also the thickness of the membrane, from 1 to 546 days of age. At the bottom of each column are given the ratios of the breadth at 1 to 546, 12 to 546, and 20 to 546 days. While the ratio between 1 and 546 days is 1.7, those from 12 to 546 days and 20 to 546 days diminish to about 1:1.0, that is the membrane at twelve days has attained about its full breadth, and there is only a very gradual increase in its breadth with advancing age. After twelve days similar ratios are found for the separate zones as well.

From 1 to 546 days the ratios for the two zones differ con- siderably; that for the second zone is 1:1.2 and that for the first is 1:3.6. This is due to the fact that in the cochlea at birth the development of the labium vestibulare is incomplete, even in the basal turn, while at the apex we can very often hardly see the invasion of the mesenchymal tissue in the inner part of the greater epithelial ridge.

At every stage the outer zone is broader than the inner; the ratio between them at birth is 1:3.8. This diminishes to 1:1.25 at twelve days, after which age it remains practically constant. Owing to the form of the membrana tectoria and to its great sensitiveness to the method of preparation, it is difficult to obtain good values for its thickness.

Generally speaking, the membrane is thickest about midway between the outer edge of the labium vestibulare and the inner boundary of the inner hair cell, and it was here the measurements given in table 4 were made. As shown in this table, the thickness increases rather rapidly from birth to twenty days, but after that period remains approximately constant.


30


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


As we know, the radial breadth of the membrane increases gradually from the basal to the apical turn. Table 5 (charts 4, 5, and 6) shows how the breadth of the total and of each part of the membrane changes in successive turns from base to apex according to age. At birth it is broadest in the beginning of the middle turn (turn II) decreasing gradually towards the apex. From three to twenty days the greatest breadth is usually found

TABLE 4

Average radial breadth of the membrana tectoria and its thickness in radial-vertical section. Averages of all four turns (charts 2 and 8)


AGE


BODT WEIGHT


BODY LENGTH


Outer zone between free end of mem- brane and labium


Inner zone labium vestibulare and inser- tion of mem- brane


Total length of mem- brane


Ratios inner and outer zone


Thickness membrane


days


grams


mm.


M


M


M



M


1


5


48


140


37


177


1 3.78


12


3


8


56


134


94


228


. 1.43


32


6


11


63


154


105


259


1.44


32


9


10


58


158


123


281


1.28


27


12


13


60


157


126


283


1.25


25


15


13


75


160


124


284


1.29


28


20


29


95


162


129


291


1.26


38


25


36


104


162


128


290


1.27


34


50


59


125


162


131


293


1.24


35


100


112


159


162


132


294


1.23


36


150


183


190


161


131


292


1.23


32


257


137


175


163


129


292


1.26


38


366


181


191


162


131


293


1.24


35


546


255


213


163


132


295


1.23


34


Ratios 1 546 days


1 1.2


1 3.6


1 1.7



1 2.8


t 12 546 "


1.0


1.0


1.0



1.4


20 5 "


1.0


1.0


1.0



0.9


in turn III, but after this in turn IV. At the bottom of each column are given the ratios of the radial breadth in each turn between the several age limits.

These show that after twelve days there is but little change in the radial breadth of the entire membrane in any turn.

On examining the growth in each zone of the membrane through the several turns, we find that after three days the outer zone of the membrane becomes at each age always broader from base to apex.


31


u


200


150


100


50


o


AGE QAYSH i i


O


25


50


5O 10O 2OO 3OO 4OO 50O


Chart 2 The radial breadth of membrana tectoria, table 4, figure 1. Total radial breadth of the membrane.

Radial breadth of outer zone.

  • - Radial breadth of inner zone.


40 M 20

n








































































i


V,
















^


9 ~~



  • .


c=















/













"^


--











1


^

































/































































































































G


E


C


A


4~





























!


25 50 50 10O 2OO 3OO 4OO 5OO

Chart 3 The thickness of membrana tectoria, table 4.


32


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


ta o

i-

< -S


a

2 S BS


.


n w

it


T^cOTtiCO-'^ -HOOOOOO


o; (


o;^ ^-^


(N 00


OOOOOOOO


co o !o


rH O


rH O


>> ^

c3


1 O I


rH'HCScouv.S "3:uj W i i ' co


20-546


GBOWTH OF THE INNER EAR OF ALBINO RAT


33


The values at birth are relatively greater than those at three days, as noted above, due to the undevelopment of the labium vestibulare. The inner zone grows in a like manner in breadth, but not so rapidly as the outer zone, and hence its relative breadth diminishes gradually from base to apex.

Table 6 shows these relations. While the ratios in the inner zone decreases from base to apex, those in the outer zone increase. Thus the ratios in the inner and outer zones according to the turns go in opposite directions. As stated above, the radial breadth is generally larger in the outer zone, but this relation is, in general, reversed in turn I, table 5.

TABLE 6 Condensed Ratios of the radial breadth of each zone of the membrana tectoria




Ratios according to turns of the cochlea






Ratios between inner and



BOOT


INNER CONE


OUTER ZONE


outer zone


AGE


__ fjfi**T







Turns


Turns


Turns




I-II


I-III


I-IV


I-II


I-II I


I-IV


I


II


in


IV


days


grams












1


5


1:0.8


1:0.5


1:0.0


1:1.2


1:1.3


1:1.4


1:1.8


1:2.8


1:4.3


1:0.0


8


11


0.9


0.9


0.8


1.4


1.8


1.9


0.8


1.2


1.6


2.0


18


21


0.9


0.9


0.8


1.4


1.8


2.0


0.8


1.1


1.5


1.9


203


160


0.9


0.9


0.8


1.4


1.7


2.0


0.8


1.1


1.5


1.8


In turn I the average ratios are, after eight days, smaller than 1.0; therefore, the inner zone is wider than the outer in turn I. It increases in all ages from turn II toward the apex.

In table 7 are given the ratios between each turn of the cochlea. The ratios after nine days of age are practically constant according to age, but those between turns I and II are always smaller than the others; the ratios for the two latter being alike. The ratio at one day is, however, an exception, as stated already.

As the measurements show, the membrana tectoria is at birth relatively undeveloped; it is thin and immature. After birth it increases rapidly during the first nine days, a statement which applies generally to the postnatal growth of the organs of the albino rat. Thus we get a ratio of the radial breadth 1 :1 .7 between 1 and 546 days, but after twelve days the ratios remain prac- tically 1:1.0. (Table 4.)


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


It is not my purpose to describe the fetal development of the membrana tectoria, but it is worth while to consider briefly the zones which compose the membrane; in other words, the parts of the tympanic wall from which it originated. There are chiefly

TABLE 7

Ratios of the radial breadth of the membrana tectoria according to the turns of the

cochlea


AGE


BODY WEIGHT


Ratios according to turn of the cochlea


I-II


I-II I


I-IV


days


gms.





1


5


1 1.0


1 1.0


1 :0.9


3


8


1.2


1.2


1.2


6


11


1.2


1.4


1.3


9


10


1.1


1.3


1.3


12


13


1.1


1.3


1.3


15


13


1.1


1.3


1.3


20


29


1.1


1.3


1.3


25


36


1.1


1.3


1.4


50


59


1.1


1.3


1.3


100


112


1.1


1.3


1.4


150


183


1.1


1.3


1.3


257


137


1.1


1.3


1.3


366


181


1.1


1.3


1.3


546


255


1.1


1.3


1.3


Chart 4 The total radial breadth of membrana tectoria arranged according to the turns of the cochlea, table 5.

About middle part of the basal turn (I).

About the beginning of the middle turn (II).

About the middle part of the middle turn (III).

About the beginning of the apical turn (IV). 2

Chart 5 The radial breadth of the inner zone of the membrana tectoria,

according to the turns of the cochlea, table 5.

Chart 6 The radial breadth of the outer zone of the membrana tectoria,

according to the turns of the cochlea, table 5.

  • In most cases when the values which have been determined are analyzed

according to the turns of the cochlea, it is found that they increase with later growth from the basal (I) to the apical (IV) turn and in the order just given in chart 4. Owing to this uniformity of behavior, some thirteen charts showing the several values according to turn have been omitted, since the graph given by the average value is sufficiently informing in each instance.

In the case of those charts which have been retained, and in which the measurements are according to the turns of the cochlea, the respective turns I-IV are recorded by characteristic lines similar to those used for them in chart 4, and in these cases the further designations of the turns are omitted.


350


300


I


ISO


G.E DAYSH




25 5O


50 1OO 2OO 30O 400 500

Chart 4


150


1OO


50




AGE


25 50 50 1OO 200 300 4OO 500

Charts


180


100


DAYS-


25 50 5Q 1OO 2OO 3OO 4OO 5OO

Chart 6


36

two views about this. While a few authors, Kolliker ('67), Hensen ('63), and recently Hardesty ('08, '15), and others hold that only the greater epithelial ridge takes part in the formation of the membrane, most investigators (for example, Bottcher, '69; Retzius, '84; Rickenbacher, '01; Held, '09; Van der Stricht, '18) consider that it originates from both the greater and lesser epithelial ridge. My figure 5, supports the latter view; that is, while the main part is developed from the greater ridge, the outer narrow marginal part is secreted from the lesser ridge.

The figure in Quain's Anatomy by Schafer ('09) (vol. 3, part 2, p. 332, llth ed.,) is from the earlier paper of Hardesty and shows the membrane in the pig as arising from the greater epithelial ridge only.

Hardesty has corrected this figure in his paper published in 1915. Thus in the very early stage after birth in these forms we have three zones, an inner, an outer, and a marginal zone. With age, however, this marginal zone becomes, as Held ('09) and others agree, gradually smaller and smaller, and finally it is difficult to differentiate it from the outer zone. Thus for convenience in measurements I have treated the membrane as consisting of two zones only.

Comparing the breadth of the inner and outer zones, it is evident that the outer is always the broader. The ratio is (table 4) at birth 1 : 3.78, at three days 1 : 1.43, and then gradually diminishes to 1:1.23 with age.

Now if we examine the ratios of the total breadth of the membrane according to the turns of the cochlea, we find after six days that the ratio generally increases from base to apex, and that these ratios remain nearly constant after nine days of age, as shown in table 7.

Thus the ratio between turns I and II is 1:1.1; between turns I and III, 1:1.3; between turns I and IV, 1:1.3. The breadth of the membrane increases, -therefore, in the albino rat gradually from the base to the middle part of the middle turn; from this point it does not increase to the apex.

Since the breadth at the tip of the apex diminishes greatly, as is generally recognized, Hardesty ('08) found in the pig the following ratios (table 8):


GROWTH OF THE INNER EAR OF ALBINO RAT


37


Comparing these ratios obtained by Hardesty in the pig with mine, there appear to be large differences between them. The reason for these I will discuss later.

When we consider the breadth in each part of the membrane according to the turn, we find that the increase of the breadth of the membrane in each turn is due to the development of the outer zone. The inner zone, which is adherent to the labium vestibulare, does not increase in the rat as Hardesty ('08/15) found to be the case for the pig, but on the contrary decreases from base to apex a relation found by Retzius ('84) in the rabbit, cat, and man and confirmed by Rickenbacker ('01) in the guinea- pig. On the contrary, the outer zone increases in breadth from

TABLE 8 Ratios of the breadth of the membrana tectoria according to turn of cochlea (Hardesty)


Kind of animal


Preparation method


Ratios between breadth in 7 and 5 half turn


Ratios between 7 and 3 half turn


Ratios between 7 and 1 half turn


Pigs two weeks of age


Membrane teased out Membrane


1 : 1.4


1 :1.7


1 :2.5



teased out


1 :1.8


1 :2.5


1 :2.7


Adult


Membrane in






section


1 : 1.6


1 :2.1


1 :1.8


base to apex, and in each stage the ratios between the successive turns are nearly the same. These ratios between successive turns, however, show rather large differences according to the different authors.

My results (table 5) show that the outer zone in the albino rat is nearly two times wider at the apex than at the base. This agrees with what von Ebner ('02) finds in the human cochlea.

When we consider the thickness of the membrane, we find it thin at birth, but at three days (table 4) it increases rapidly and reaches almost its greatest thickness. This increase in thickness arises through the apposition of new layers to the under surface, as Hasse (73) and others have noted, but very large differences appear between the figures given by various authors.


38 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON

Kolliker ('67) finds the membrane 45 n thick in the ox. In the guinea-pig it is 15 ^ in the thickest place, according to Schwalbe ('87). Middendorp ('67) gets in mammals generally a very thin membrane, about 1 n thick. Retzius ('84) states that in the thickest part in the rabbit it measures 27 [x, in the cat 32 to 50 |x, and in man 24 to 25 [x. Hardesty finds in the young pig an average thickness of the teased membrane of 50 [x and in an adult hog 119.3 (x. I get 35 (x as an average in the adult albino rat after twenty days of age, varying from 32 to 38 [x. My result is therefore closest to that for the cat as obtained by Retzius. These results are plainly influenced b.y the dissimilar technical methods used by the several investigators.

About the outermost end of the membrane there are still two different views. One view is that the outer end of the membrane projects beyond Hensen's prominence; Kolmer ('07; pig, calf goat and horse); Hardesty ('15; pig, hog) Shambaugh ('10; pig). Others assert that the membrane terminates with its outer edge at the outer boundary of the outermost series of the outer hair cells. My preparations show that in the rat the outer end of the membrane does not reach Hensen's prominence.

Possibly this difference is due to the technique of preparation. In the figures drawn by many authors we can recognize many artifacts and postmortem changes in the cochlea. Even in the figures of Kolmer ('07) we see these changes, although he injected the fixing solution through the carotid artery. Held ('09) says in his criticism of Hardesty 's figures that " figures 6 and 7 wie schon Hardesty selbst vermutet hat, sicherlich auf einer Ver- quellung beruhen "

I myself never observed such a gigantic membrane as Hardesty ('08, '15), Shambaugh ('10), and others show in the cochlea of the pig. On the other hand, I cannot absolutely deny that there may have been shrinkage in the cochleas prepared by my methods, though I see no evidence of it.

From our present knowledge, however, the method of vital fixing is considered the best available, as already maintained by Siebenmann and Yoshii ('08), Metzner and Yoshii ('09), Nager and Yoshii ('10), Wittmaack and Laurowitsch ('12), and others.


GROWTH OF THE INNER EAR OF ALBINO RAT 39

By using this vital-fixation method we get perfect sections which can be used to solve the problem of the shifting of the organ of Corti an event which I will discuss later.

2. Membrana basilaris. The membrana basilaris of the cochlea stretches between the limbus laminae spiralis and the ligamentum spirale. The acoustic terminal apparatus is situated on it and according to the dominant Helmholtz-Hensen theory, this membrane is to be considered as very important in tone perception. The row of the fine holes, foramina nervina, is generally designated as the inner boundary of this membrane. Strictly speaking, however, the beginning of the membrane is at the outer edge of the labium tympanicum, which sharpens at first beyond the foramina nervina and passes over to the sub- stance of the membrana basilaris. Practically it is almost impossible to decide exactly the point of transition. Thus I have used in the measurement of the membrane the foramina of the habenula perforata as an inner limiting line following in this Retzius, ('84) Schwalbe ('87), and others. Here it is to be mentioned that the organ of Corti lies with its inner portion not only upon the inner part of the membrane, but extends to the foramina nervina also.

The membrana basilaris is usually divided into two portions; the inner, termed the zona arcuata, and the outer, the zona pectinata. The former stretches from the habenula perforata across the base of the tunnel of Corti to the outer edge of the foot of the outer rods of Corti ; the latter extends from this point to the ligamentum spirale (fig. 2), 5= inner zone, 10= outer zone.

In table 9 (chart 7) are given the values for the total radial breadth of the membrane, that of each zone, and the ratios between them. At the bottom of each column are given the ratios at 1 to 546, 12 to 546, and 20 to 546 days of age. In the total radial breadth of the membrane, as the table shows, there are large differences on age from birth to nine days. Between 1 day and three days the increase is 30 |x and between three days and six days, 28 [A. After nine days the breadth increases more slowly but continuously to old age.


40


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


In the growth of both zones we see about the same relation. These increase rapidly from birth till nine (or twelve) days and after that very slowly. These relations are shown clearly in the ratios at 1 to 546, 12 to 546, and 20 to 546 days. While after twelve days the ratios in total breadth and in each zone are the same, 1:1.1, that for 1 to 546 days is smaller for the outer zone than it is for the inner zone, thus the inner zone increases

TABLE 9

Radial breadth of Ihe membrana basilaris measured between the foramina nervina and ligamentum spirale in radial sections on age (chart 7, fig. 2}


AGE


BODY WEIGHT


INNER ZONE

(Zona arcuata)


OUTER ZONE

(Zona pectinata)


Total radial breadth of the mem- brane


Ratios between the radial breadth of the inner and outer zone


days


grams


P


M


M


M


1


5


49


75


124


1 1.5


3


8


63


91


154


1.5


6


11


77


105


182


1.4


9 1


10


79


111


190


1.4


12


13


- 88


100


188


1.1


15


13


87


102


189


1.2


20


29


86


106


192


1.2


. 25


36


87


108


195


1.2


50


59


88


107


195


1.2


100


112


92


106


Id8


1.2


150


183


92


107


199


1.2


257


137


92


107


199


1.2


366


181


93


111


204


1.2


546


255


94


113


207


1.2


Ratios 1 546 days


1 1.9


1 1.5


1 1.7



12546 "


1.1


1.1


1.1



20546 "


1.1


1.1


1.1



1 A rat of nine days which could hear, gave the following:


Right side 11


94


103


197




91


104


195




93


104


196


1 : 1.1


considerably after birth, while the outer zone does not grow, as some authors have imagined, as much as the inner zone. I will discuss this point later.

Comparing the growths of the radial breadth of the inner and outer zones, we find that the inner zone is relatively narrow at nine days; thus the ratios between them are 1:1. 4; after that period the inner zone increases rapidly, and even at twelve days the ratio becomes 1:1.1, which is almost the same as in the adult, 1:1.2.


GROWTH OF THE INNER EAR OF ALBINO RAT


41


In table 10 the radial breadths of the whole membrane and of its zones are arranged accordingly to the turns of the cochlea on age. At the bottom of each column are given the ratios from 1 to 546, 12 to 546, and 20 to 546 days. We see at first that the total radial breadth at one day is largest in the basal turn; at three days it becomes larger on passing from the basal toward the II and III turns, but in turn IV it is again small.


220

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Chart 7 The radial breadth of the membrana basilaris, table 9, figure 2, distance 11.

Total radial breadth of the membrane.

Radial breadth of the zona pectinata.

Radial breadth of the zona arcuata.

After six days it is a well-known fact that the radial breadth of the membrana basilaris is narrowest in the basal, and widest in the apical turn (not the tip of the apex, but the beginning of the apical turn). These differences are not always the same between all the turns; those between I and II, and II and III are marked; those between III and IV are small. The ratios at 1 to 546 days show those for the upper turn to be largest, while from 12 to 546, and 20 to 546 days the ratios in all turns are about 1:1.1.


42


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


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Right side Left side Average


GROWTH OF THE INNER EAR OF ALBINO RAT


43


In the zona arcuata (inner zone) the same relation is to be seen in each turn; therefore, in the early period the breadth is less in turn IV than in the other turns. Very soon, however, the value in turn IV becomes the largest and diminishes toward the base. The rate of the growth of this zone, from 1 to 546 days, is also smallest in turn I, and largest in turns III or IV; the ratios being in the first 1:1.6, and in the last 1:2.1.

In the zona pectinata (outer zone) we see also similar relations.

TABLE 11

Ratios of the radial breadth of the membrana basilaris according to the turns of the

cochlea on age


AGE


BOOT WEIGHT


Ratios between turns


I-II


I-III


I-IV


days


gms.





1


5


1


1.0


1


1.0


1


1.0


3


8



1.0



1.0



1.0


6


11



1.1



1.2



1.2


9


10



1.1



1.2



1.1


12


13



1.2



1.3



1.3


15


13



1.1



1.3



1.3


20


29



1.1



1.2



1.3


25


36



1.2



1.3



1.3


50


59



1.1



1.3



1.3


100


112



1.1



1.3



1.3


150


183



1.1



1.2



1.3


257


137



1.1



1.2



1.3


366


181



1.1



1.2



1.3


546


255



1.1



1.2



1.3


Only slight differences in the ratios according to age are found.

In table 11 the ratios according to the turns of the cochlea are given. While from one to three days the ratios are the same in each turn, 1:1.0, yet after six days those for turns I to II are smallest, and for I to IV larger, thus showing slight differences between them.

In the literature we find only one description, that by Retzius ('84) touching the growth of the radial breadth of the membrana basilaris according to age. He measured this membrane in the rabbit and cat and got the following values in n (table 12).


44


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


Comparing these values with mine obtained for the albino rat, it is to be noted that those of Retzius are generally larger than those for the albino. For example, while I get at birth only 126 (x in the basal turn, Retzius ('84) obtains 180 [x in the rabbit and even 270 [x in the cat. As stated above, the radial breadth increases in the albino rat continuously with age. It is very peculiar to find in the Retzius table that the breadth of the membrane in the cat is decidedly larger at birth than at three and seven days. The average value for the new-born is 315 [x, which is larger than at thirty days, which is 310 [x.

Retzius ' data show the membrane in the rabbit and cat always wider in the apical than in the basal turn at birth and at two

TABLE 12 Breadth of membrana basilaris according to turns, p. (From Retzius, '84}


RABBIT


CAT


Age


Basal


Middle


Apical


Basal


Middle


Apical


days








New-born


180


270



270


300


375


2


220


272


280






3





.


200


280



7


270


306



211


258


300


10


255


310


390






11






255


300


330


14


300


360


410






30






240


300


390


days. My results, given in table 10, show the reverse at the ages of one and three days. This is an expression of greater immaturity in the case of the rat.

In comparisons like the foregoing, several conditions must be kept constantly in view.

So far as absolute values are concerned, it is to be expected that these would be unlike in the different mammals, because the cochleas differ in size. As to the relations between the values at birth and at maturity, it is plain that these cannot be ex- pected to agree unless the cochleas of the animals compared are in the same phase of development at birth. In the foregoing instances it appears that the cat is relatively precocious, as compared with the rabbit, while, as might be expected, because


GROWTH OF THE INNER EAR OF ALBINO RAT


45


of their closer zoological relationship, the rat and the rabbit are in better agreement, although the rabbit appears to be a trifle more advanced at birth than the rat.

Finally, in the comparison of different series of data, differ- ences due to the lack of homogeneity in the series of animals used and to the various techniques employed can hardly fail to play an important part, and allowance must be made for these disturbing factors.

When we consider the rate of growth, the ratio of a one to a fourteen-day-old rabbit is 1:1.6, according to Retzius; therefore,

TABLE 13 Breadth of basilar membrane


ANIMAL AUTHOR


TURN IN WHICH MEASUREMENT WAS MADE IN M


Basal


Second


Third


Fourth


Average


Man-New-born







Hensen ('63)


235


413



495


381


Man Mature







Retzius ('84)


210



340


360


303


Calf







Kolmer ('07)


200


280



400


293


Pig







Kolmer ('07)


168


200


256


304


232


Goat







Kolmer ('07)


124


384


432



313


Cat







Bottcher ('69)


90



435



263


Cat







Middendorp ('67)






246-275


it has very nearly the value found in the albino. In the cat, however, the ratio between one and thirty days is 1:0.97; there- fore, it apparently decreases a bit.

This difference is most readily explained as due to the precocious development in the cat at birth.

On comparing the radial breadth of the membrane obtained from several mammals by various authors, we find the following values (table 13).

The values here given must be read in the light of the various modifying conditions to which reference has just been made.


46 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON

My average value after twenty days is 199 [i; therefore, it is absolutely the smallest in this series of mammals. The rat is also the smallest species examined.

As shown in the literature quoted, and also in my own results, the membrane increases in its breadth in all the mammals ex- amined from the base toward the apex a relation contrary to that reported by the older authors (Corti, '51, and others). This increase is continuous, but is at first more rapid and after- wards more gradual. The ratios of this increase in the albino rat are given in table 11.

The next question relates to the breadth of each zone of the membrane according to age. So far as I know, there is no such study in the literature, not even in Retzius. In the albino rat, as shown in table 9, each zone increases in breadth with age. The rate of growth, however, is somewhat different, and in the zona arcuata it is greater than in the zona pectinata (1:1.9 and 1 :1.5, respectively), although the absolute value is always greater in the latter.

As noted above, the membrane increases in its radial breadth from the basal to the apical turn. How, and in which portion of the membrane does this increase arise? Henle ('66) first regarded the breadth of the inner (zona arcuata) as approx- imately constant.

"Nicht nur in den verschiedenen Regionen einer Schnecke, sondern, soviel ich sehe, selbst in den Sshnecken verscheidener Tiere und des Menschen; sie schwankt nur wenig um 0.01 mm." (Eingeweidelehre des Menschen, 1866, S. 793).

In the second edition of his book ('73) he states, however, that in the increase of the breadth according to the turn, both zones seem to take part. Hensen ('63) gets in the zona arcuata of the base of the human cochlea the breadth of 19 ^ and in the apex 85 \L. Middendorp ( '68) gives in the cochlea of the cat a continuous increase of the breadth of the zona arcuata from 94 to 122.5 {A. .""'

More detailed data are given in table 14.

According to all these authors, the breadth of both the inner and outer zones increases from base toward apex and results


GROWTH OF THE INNER EAR OF ALBINO RAT


47


in the increase of the total radial breadth of the membrane according to turn. My results obtained from the albino rat agree with these data.

3. Radial distance between the habenula perforata and the inner corner of the inner pillar cells at base. The measurements of the radial distance from the habenula perforata to the bases of the inner and outer pillar cells were taken to determine their postnatal growth. As already stated, the cells from which the arch of Corti arises stand at birth nearly vertically and have no space between them (fig. 4). In the adult, however (fig. 10), we see a space, the tunnel of Corti lying between them and changes in the form of the arch occur. To follow these changes

TABLE 14 Breadth of the inner zone of the membrana baeilaria in n



NUMBER Of TURN



First


Second


Third


Fourth


Cat-adult






Bottcher ('69)


60


105


135



Guinea-pig






Winiwarter (70)


45-52


63-68


71-80


80-83


it seems at first necessary to study the growth of the pillar cells and of the other elements in the organ of Corti. At the same time we must take into consideration the inward shifting of the organ of Corti, first studied by Hensen. This shift inward of the organ is, according to Hensen, chiefly caused by the wandering of the pillar cells, especially the inner pillar cell. Therefore, it seemed necessary to determine the radial distance of the pillar cells from the habenula perforata at different ages before discussing this interesting problem.

In table 15 are given the values for the radial distances between the habenula perforata and the inner corner of the inner pillar cell at its base according to age (figs. 4 to 9). As we see, the average value increases till three days of age, then vanishes suddenly, though at six days we have a measurable interval in the upper turns of the cochlea. Comparing these distances according to the turn, they are smallest in turn I and increase


48


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


toward the apex. In some cases, at six days, we have no interval in the basal turn, but in the higher turns an interval gradually appears and at the apical turn is largest. This table shows, therefore, that the inner corner of the base of the inner pillar cell lies at birth outward from the habenula perforata at an

TABLE 15 Condensed

Radial distance between the habenula perforata and the inner corner of the inner

pillar at base on age


AGE


BODY WEIGHT


TURNS OF THE COCHLEA M


I


II


ill


IV


Aver.


days








1


5


19


22


22


23


22


3


8


23


28


28


30


27


6


11


In one case 5


In 2 cases 10


14


18





In other 3 cases


In other cases





9


10









12


13










average distance of 22 \L. At three days of age the inner corner moves farther outward with the developing membrana basilaris and the distance increases from the base to the apex. Between three to six days this outward movement not only stops, but reverses its direction, and at six days it often becomes zero in the basal turn. Bottcher ('72) finds in the cat the following values for this interval in \i (table 16).

TABLE 16


CAT EMBRYO 11 CM. LONG


ADULT CAT


I


II


ill


IV


Average


I


II


ill


IV


Average


15


39


30


30


29


3


3


3


3


3


TABLE 17


BABBIT


CAT


AGE


Basal turn


Middle


Apical


Average


Basal


Middle


Apical


Average


days










New-born


300


300


300


300


5


40


45


30


2


10


12


30


17








3








3


36





7














11











18




GROWTH OF THE INNER EAR OF ALBINO RAT 49

Retzius ('84) studied this distance in the rabbit and cat and gets the values given in Table 17.

Comparing the values of these two authors with my own, there are of course some differences. While in the rabbit the interval is large at one day, it is greatly diminished at two days of age. At three days the inner corner of the cell reaches the habenula perforata. In the cat the values are nearer to mine. The fact that the values increase from base toward apex is to be seen here also. This peculiar phenomenon appears, therefore not only in the albino rat, but also in the rabbit and the cat during the earliest stage of postnatal life.

4- The radial distance between the habenula perforata and the outer corner of the inner pillar cell (resp. the inner corner of the outer pillar cell) at base. This measurement is difficult. As we know, the inner and outer pillar cells in the albino are from birth till nine days of age in contact with each other along their whole length, and therefore they do not yet surround the space forming the tunnel of Corti. At about nine days, however, the tunnel appears while the cells remain in contact by their bases. It is almost impossible to determine the line of contact on the basilar membrane in my preparations. To get the radial distance between the habenula perforata and the outer corner of the inner pillar cell I have proceeded therefore as follows:

First, I have measured this distance directly up to nine days of age; after that this distance consists of the sum of the radial basal breadth of the inner pillar (not pillar cell) and the breadth of the inner basal cell on the basilar membrane. Since it is impossible to get the latter value directly in my sections, I considered that half of the radial distance between the outer corner of the inner pillar and the inner corner of the outer pillar would be equivalent to it.

Of course, I do not know whether the value of the sum of these two distances is at all ages, identical with the distance between the habenula perforata and the outer corner of the inner pillar cell at its base. I believe, however, that a systematic study of the growth of this distance will be significant.


50


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


In table 18 are given the values for the radial distance between the habenula perforata and the outer corner of the inner pillar at base up to nine days of age. As shown, these values, on the average, increase with age. The increase of this distance means that the base of the inner pillar cell spreads outward more and more.

When we consider this distance according to the coil of the cochlea, it is at birth about the same through all the turns (table 18; at three days it increases up to turn III, and in turn

TABLE 18

Radial distance between the habenula perforata and the outer corner of the inner

pillar at base on age




TURNS OF COCHLEA M


AGE


BODY WEIGHT


I


II


III


VI


Average


days


grams







1


5


40


41


39


39


40


3


8


48


49


50


48


48


6


11


38


45


58


53


49


9


10


44


46


56


53


50


IV the value is the same at the apex as at the base. At six days the value in turn III is also largest, and next largest in turn IV. At nine days of age the same relations are to be seen.

In table 19 (chart 8) are given the values for the radial basal breadth of the inner pillar (not pillar cell) on age. At the bottom of the last column are the ratios from 6 to 546, and 20 to 546 days. As above noted, the rod can be followed at birth from the upper part to near the base of the cell (fig. 4). At three days (fig. 5), its base reaches the basilar membrane as a thin and slender thread, but we cannot measure its basal breadth accurately. During the next few days it increases in radial breadth rapidly, and at six days has the average value of 29 [/. (table 19). After nine days it decreases distinctly till twenty days, after which the value remains nearly constant. These relations are evident in the ratios. While the breadth at six days is about twice that at 546 days, that at twenty days has the same value.


GROWTH OF THE INNER EAR OF ALBINO RAT


51


According to the turn of the cochlea, the values from nine to fifteen days become gradually larger on passing from the base toward the apex. After twenty days, however, this relation vanishes, and the values become nearly the same through all

TABLE 19 Radial basal breadth of the inner pillar on age (chart 8)


day*

1

3

ti

9

12

15

20

25

50

100

150

257

366

546

Ratios 6 20


WEIOHT BODY


TURNS OF THE COCHLEA M


I


II


III


IV


Average


grams







5









8









11


29


31


27


27


29


10


28


28


33


35


31


13


18


19


22


25


21


13


18


18


19


19


19


29


14


15


15


15


15


36


14


15


14


15


15


59


14


14


14


13


14


112


14


14


14


13


14


183


15


15


15


15


15


137


15


15


15


15


15


181


16


17


15


15


16


255


15


14


16


15


15


-546 days






1 :0.5


-546 "






l.o


40 U 20

n








































































































































"





































































\


























































































Ab



DA'


/q





























a


25 5O 5Q IOO 20O 3OO 4OO 5OO

ChartS. The radial basal breadth of the inner pillar (not pillar cell), table 19, figure '2, distance 3.

the turns. In table 20 the ratios of the turns I to II, I to III, and I to IV are given for three age groups (condensed from table


52


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


From the data given by Retzius ('84) we get the values in jx of the radial basal breadth of the inner pillar in the rabbit and cat as follows (table 21).

Comparing these values with my own, it is to be noted that Retzius' measurements in the rabbit agree perfectly at the earliest stage with those in the albino rat. Also we find in the


TABLE 20 Condensed


Ratios of the radial basal breadth of the inner pillar according to the turns of the

cochlea on age




RATIOS


BETWEEN TTTBN8



AGE


BODY WEIGHT


I-II


I-III


I-IV


days


grams





8


11


1 1.0


1 1.0


1 1.1


14


13


1.1


1.2


1.3


189


124


1.0


1.0


1.0


TABLE 21

Radial basal breadth of inner pillar in n (Retzius)


BABBIT


CAT


Age


Basal turn


Middle


Apical


Average


Basal


Middle


Apical


Average


days










New-born








11






2














3








12






7


15


12


15


14


10


15





10


17


18


18


18








11








15


15





14


15


15


12


14








30








9


12


15


12


rabbit at seven days values homologous with those obtained in the albino rat at fifteen days of age, only in the rat the breadth is absolutely greater. In the cat the values at seven days of age are about the same, or a bit smaller, than those in the albino rat. Here again the rabbit is a trifle more precocious than the rat, and the cat much more so.

Table 22 (chart 9) shows the values for the radial distance between the outer corner of the inner pillar (not pillar cell)


GROWTH OF THE INNER EAR OF ALBINO RAT


53


TABLE 22

Radial distance between the outer corner of the inner pillar and the inner corner of the outer pillar at base on age (chart 9)


AGE


BODY WEIGHT


TURNS OF THE COCHLEA M




I


II


III


IV


Average


days


grams







1


5









3


8









6


11


25


28


29


34


29


9


10


27


30


35


30


31


12


13


37


41


51


53


46


15


13


35


46


56


56


48


20


29


43


53


66


68


58


25


36


42


58


67


68


59


50


59


41


54


68


74


59


100


112


44


59


71


78


63


150


183


43


59


68


76


62


257


137


46


56


66


75


61


366


181


45


57


68


74


61


546


255


47


60


71


74


63


Ratios 6546 days 12546 " 20546 "


2.2 1.4 1.1


ou

14,

60 40 20

r\






















































































































<




t=



-



MM



.


=







-






1



















/

































i


































/


































































i


































1































































































































































G


E


DA>


/C





























1


13


o


25


50


50 1OO 20O 3OO 40O 5OO


Chart 9. The radial distance between the outer corner of the inner pillar (not pillar cell) and the inner corner of the outer pillar (not pillar cell) at base, table 22, figure 2, distance 6.


54


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


and the inner corner of the pillar (not pillar cell) at the base, on age. At the bottom of the last column are given the ratios from 6 to 546, 12 to 546, and 20 to 546 days. As just stated, the inner, and especially the outer rods, do not appear in the respective pillar cells at the earliest stage, the latter becoming evident a bit later than the former. After six days of age the distance between them can be determined.

As table 22 shows, this distance increases at first rapidly, then more slowly with age. This agrees with the growth of the membrana basilaris, as already noted. While the value at 546 days is over twice as large as at six days, it is but little larger than at twenty days, as the ratios show. Moreover, the distance increases from the base toward the apex rapidly up to turn

TABLE 23 Condensed

Ratios of the radial distance between the outer corner of the inner pillar and the inner corner of the outer pillar, at base according to turns of the cochlea on age




BATIO8 BETWEEN TURNS




I-II


i-m


I-IV


days


grams





8


11


1 : 1.1


1 : 1.2


1 : 1.2


14


13


1.2


1.5


1.5


189


124


1.3


1.5


1.7


III and less rapidly to turn IV. This relation is more concisely presented in table 23. Retzius ('84) gives the value of this distance in the rabbit and the cat as follows (table 24).

The table 24 shows that there is no measurable distance between the outer corner of the inner pillar and the inner corner of the outer pillar at the very early stage in the rabbit, and this result is like that for the albino rat. Later the distance is larger in the rabbit than in the rat. The rate of increase of the values from the base to the apex is, however, similar in both forms. In the cat, on the other hand, there is already at birth a large distance between the pillars. The cochlea of the cat is there- fore at this period more advanced in this character than that of the rabbit or rat, but in the cat also the distance tends to in- crease from the base toward the apex.


GROWTH OF THE INNER EAR OF ALBINO RAT


55


In table 25 (chart 10) are given the values for the radial distance between the habenula perforata and the outer corner of the inner pillar cell (resp. the inner corner of the outer pillar cell) at the base according to age. This table is derived from tables 18, 19, and 22. The values from one to nine days of age are from table 18. Those after twelve days consist of the sum of the values in table 19 plus the one-half of those given in table 22 (fig. 2 value for bracket 3 plus one-half the value for bracket 6).

TABLE 24

Radial distance between the outer corner of the inner pillar and inner corner of the

outer pillar in n (Retzius)


RABBIT


CAT


Age


Basal turn


Middle turn


Apical turn


Average turn


Basal turn


Middle turn


Apical turn


Average turn


days










New-born








64






2














3








45






7


57


75


75


69


50


75





10


52


72


74


66








11








75


95





14


63


100


99


87








30








66


93


90


83


The values increase gradually after birth till nine days, when they reach a maximum, and then decrease, but increase again very gradually till old age. If this method of measurement is accepted, then the inner corner of the inner pillar cell lengthens inward at the base in the earlier stages. At the time when the inner pillar reaches the habenula perforata, the outer corner of the inner pillar has not yet moved inward, and thus the breadth of the base is largest. After the inward wandering of the inner pillar cell, the base diminishes a little in its breadth; then it increases slightly with advancing age.

When considered according to the turn of the cochlea, this measurement generally increases from the base to the apex, but more rapidly from turn I to turn III, and only slightly from


56


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


TABLE 25

Radial distance between the habenula perforata and the outer corner of the inner

pillar cell (resp. the inner corner of the outer pillar cell) at base on

age. Derived from tables 18, 19 and 22 (chart 10)


AGE


BODY WEIGHT


TURNS OF THE COCHLEA M


I


II


III


IV


Average


days


grams







1


5


40


41


39


39


40


3


8


46


49


49


49


48


6


11


38


45


58


53


49


9


10


44


46


56


53


50


12


13


36


45


50


50


45


15


13


36


41


47


47


43


20


29


36


42


48


49


44


25 .


36


35


44


48


49


44


50


59


35


41


48


50


44


100


112


36


44


50


52


46


150


183


36


45


49


53


46


257


137


38


43


48


51


45


366


181


39


45


49


52


46


546


255


39


44


52


52


47


Ratios 1 546 days 9546 " 12546 " 20546 "


1.2 0.9 1.0 1.1


60

JLL

40 20

c\








































































































^


r*


r^





_ !


1

















e=







-_



















































































































































































































































G


^


c


A


/s-






























25


50


50 1OO 2OO 3OO 4OO 5OO


Chart 10 The radial distance between the habenula perforata and the outer corner of the inner pillar cell (resp. the inner corner of the outer pillar cell) at base, table 25, figure 2, distance 8.


GROWTH OF THE INNER EAR OF ALBINO RAT


57


turn III to IV. Table 26 shows this relation. While at birth the ratio is in all turns the same, 1 :1.0, at other ages it is always higher. Retzius ( '84) gives the results obtained from the rabbit and the cat as follows (table 27).


TABLE 26 Condensed


Ratios of the radial basal distance between the habenula perfcrata and the outer

corner of the inner pillar cell (resp. the inner corner of the outer pillar

cell) at base on age according to the turns of the cochlea




RATIOS BETWEEN TURNS


AGE


BODY WEIGHT





I-I1


I-HI


I-IV


days


gram*





1


5


1 1.0


1 :1.0


1 :1.0


8


11


1.2


1.4


1.3


18


21


1.2


1.3


1.3


213


138


1.2


1.S


1.4


TABLE 27


Distance between the habenula perforata and the outer corner of the inner pillar

cell in n (Retzius)


Age


Basal turn


Middle

turn


Apical turn


Average turn


Basal turn


Middle turn


Apical turn


Average turn


days










New-born


30


45


39


38


60


60


60


60


2


30


36


30


32








3








44


60





7


37


46


45


43


45


69(?)


65


60


10


39


52


48


46








11








60


66


75


67


14


40


54


51


48








30









60


60




At the earlier stage this distance in the rabbit is a little less than in the rat. Soon after, however, it becomes about the same. In the cat the values are generally larger than in the rat.

5. Radial basal breadth of the outer pittar cett (including the outer pillar). The measurement of the radial basal breadth of the outer pillar cell is difficult. At the earlier stage, in which the inner and outer pillar cells are in contact with each other along


58


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


Radial basal breadth of the outer pillar cell (including the outer pillar) from one

to nine days of age




TURNS OF THE COCHLEA M


AGE


BODY WEIGHT





I


II


III


IV


Average


days


grams







1


5


10


9


8


8


9


3


8


15


16


15


12


15


6


11


26


28


28


33


28


9


10


26


30


30


35


30


TABLE 29 Radial basal breadth of the outer pillar on age (chart 11)


AGE


BOOT WEIGHT


TURNS OF THE COCHLEA M


I


II


III


IV


Average


days


grams







1


5









3


S









6


11


10


14


16


17


14


9


10


15


18


18


21


18


12 .


13


14


23


25


22


21


15


13


17


21


23


20


20


20


29


13


13


16


15


14


25


36


14


13


14


14


14


50


59


14


14


15


14


14


100


112


14


15


16


15


15


150


183


15


15


15


16


15


257


137


15


16


17


17


16


366


181


15


16


17


18


16


546


255


16


15


17


17


16


Ratios

1 2

40 A 20

n


6546 days 1 2546 " 0546 "


1.1 0.8 1.1












































































































































t



\,









1


-=a


<



-<










,





























































G



D


A'


^































i


25


50


5O 1OO 2OO 300 4OO 500


Chart 11 The radial basal breadth of the outer pillar (not pillar cell) table 29, figure 2, distance 7.


GROWTH OF THE INNER EAR OF ALBINO RAT


59


their whole length, we can easily measure this distance. After twelve days, however, the breadth consists of the sum of the radial breadth of the outer pillar and the half of the radial distance between the outer corner of the inner pillar and the inner corner of the outer pillar, as previously explained.

In table 28 are given the values for the radial basal breadth of the outer pillar cell (including the outer pillar) from birth to nine days of age. These values show a rapid increase. Ac- cording to the turn of the cochlea, the breadth at birth diminishes from the base to the apex. At three days it increases already in turn II, but at the later ages it increases gradually from the base to the apex.

TABLE 30 Condensed

Ratios of the radial basal breadth of the outer pillars on age according to the

turns of the cochlea




RATIOS BETWEEN TURNS


AGE


BODY WEIGHT





I-II


I-III


I-IV


days


grams





8


11


1 -1.2


1 1.3


1 1.5


14


13


1.4


1.5


1.3


189


124


1.0


1.1


1.1


In table 29 (chart 11) are given the values for the radial basal breadth of the outer pillar (not pillar cell). As in the case of the inner pillar, here also the outer pillar first appears distinctly at six days of age. After the continuous increase of the values till twelve to fifteen days, they decrease suddenly at twenty days, and then increase again very slowly. This relation is clearly shown by the ratios at the bottom of the last column. That the values tend to increase from the base toward the apex is also shown, though there are some exceptions. Table 30 gives the condensed results.

From Retzius' work ('84) we have calculated the values for the radial basal breadth of the outer pillar in the rabbit and cat as follows (table 31).

There are large differences between my results and those of Retzius during the earlier stage, especially in the rabbit.


60


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


At birth, the inner pillar has not yet distinctly developed at the base of the pillar cell in the rabbit and the rat, as above stated. We know that the development of the elements of the cochlea proceeds generally from the axis to the periphery, as

TABLE 31

Radial basal breadth of outer pillar measured in n (from Retzius)


RABBIT


CAT


Age


Basal turn


Middle turn


Apical turn


Average


Basal turn


Middle turn


Apical turn


Average


days


,









New-born


15?


12?


7?


11?


25


15





2


50


45


44


46








3








20






7


28


28


17


24


18


20


18


19


10


31


30


37


33








11








30


19





14


28


25


18


24








30








10


15


15


13


TABLE 32


Radial basal breadth of the outer pillar cells on age, based on tables 22, 28, and

29 (charts 12 and 18)


AGE


BODY WEIGHT


TURNS OP THE COCHLEA M


I


II


III


IV


Average


days


grams







1


5


10


9


8


8


9


3


8


15


16


15


12


15


6


11


26


28


28


33


28


9


10


26


30


30


35


30


12


13


33


38


48


52


43


15


13


35


44


50


48


44


20


29


35


40


49


49


43


25


36


35


42


48


48


43


50


59


35


41


49


51


44


100


112


36


45


52


54


47


150


183


36


45


49


54


46


257


137


38


44


50


53


46


366


181


38


43


51


55


47


546


255


40


45


53


54


48


Ratios 1 546 days

9546 " 12546 " 20546 "


1 :5.4

1.6
1.1
1.1


GROWTH OF THE INNER EAR OF ALBINO RAT


61


Held ('09) and others have pointed out. Yet, according to Retzius, the outer pillar develops in the rabbit earlier than does the inner pillar. This result seems to me very peculiar, but, at present, I am unable to explain it.

In table 32 (charts 12 and 13) are given the values for the radial basal breadth of the outer pillar cells. These data are


ou

M. 40

20







































































.-'


-


>-i






^





-








a*





-^













































































'


































































1


































/


































r~




























G



DA >


/c































25 50 50 1OO 20O 30Q 4(X) 5QO


Chart 12 The radial basal breadth of the outer pillar cell, table 32, figure 2, distance 9.



5O 50 1OO 2OO 30O 40O 50O


Chart 13 The radial basal breadth of the outer pillar cell, according to the turns of the cochlea, table 32, figure 2, distance 9.

derived from tables 22, 28, and 29. At the foot of the last column are given the ratios from 1 to 546, 9 to 546, 12 to 546, and 20 to 546 days. The values increase rapidly during the earlier stage, but after twelve days very slowly, as the ratios show. The breadth is, at birth, largest in the basal and smallest in the apical turn. Very soon, however (six days), the reverse


62


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


relation appears, and the breadth increases from the base to turn III relatively rapidly, but from turn III to IV slowly. In table 33 the ratios are given in a condensed form. The radial breadth of the outer pillar cells as given by Retzius ('84) are as follows (table 34.)

TABLE 33 Condensed

Ratios of the radial basal breadth of the outer pillar cells on age according to

turns of cochlea




RATIOS BETWEEN TtTRNS


AGB


BODY WEIGHT





I-II


i-in


I-IV


days


grams





1


5


1 :0.9


1 0.8


1 :0.8


8


11


1 1.1


1.2


1.3


18


21


1.2


1.4


1.4


213


138


1.2


1.4


1.4


TABLE 34 Radial basal breadth of the outer pillar cells in n (Retzius)


RABBIT


CAT


AOE


Basal turn


Middle turn


Apical turn


Average turn


Basal turn


Middle turn


Apical turn


Average turn


days










New-born


21


22


23


22


36


30


30


32


3


30


40


30


33








3








36


30





7


65


66


60


64


36


54


36


42


10


52


60


69


60






'


11








50


60


18


43


14


57


80


80


72








30









60


60




This table shows that the breadth of the outer pillar cell in- creases in the rabbit and the cat continuously from birth to old age, as I have found in the rat. Also the value is generally smallest in the base, largest in the apex, though there are some exceptions. The main differences between the results of Retzius and mine is that the values in the rabbit are larger than in the rat. This is probably due to the differences in the size of the animals.


GROWTH OF THE INNER EAR OF ALBINO RAT 63

6. The radial distance between the habenula perforata and the outer border of the foot of the outer pillar cell. The deter- mination of this distance is deemed necessary not only as a datum on growth in general, but also for its bearing on the difficult question of the shifting of the outer pillar cell, to be discussed later. On the other hand, this distance is identical with the radial length of the zona arcuata of the membrana basilaris (table 7. inner zone).

In table 35 (chart 14) are given the values for the radial distance between the habenula perforata and the outer corner of the outer pillar cell at base. At the foot of each column are given the ratios at 1 to 12, 1 to 20, 1 to 546, and 20 to 546 days. As table 35 shows, the distance increases continuously from birth to old age, rapidly up to twelve days, but later gradually. Up to three days the distance is slightly larger in the lower turns, but after this age the relation is reversed, and this persists through life.

The increasing ratio of the distance for each turn according to age is smallest in turn I and largest in turn IV. The ratios for the condensed data are given in table 36. While the ratio at birth is the same in each turn, 1:1.0, that of turn I to II is smallest for every condensed age. Also it is to be seen that the increase of the ratio in turn I to II is smallest and that in turns I to IV is largest. In Retzius' work ('84) we find the following values for this distance (table 37).

Table 37 shows that in the rabbit the growth changes are similar to those in the rat, though the absolute values are somewhat larger. As hi preceding determinations, the values for the cat do not stand in the same relation as those for the rabbit, but indicate precocity. Some corresponding observations by Hensen, Bottcher, and others will be presented later.

7. The greatest height of the greater epithelial ridge (der grosse Epithelwulst (Bottcher) s. Organon Kollikeri) resp. of the inner supporting cells (fig. 4, G). The so-called greater epithelial ridge is a prominence formed by high cylindrical pseudostratified cells. It is situated axialward on the tympanic wall and continued outward to the lesser epithelial ridge. About the fate of this ridge there were various divergent opinions among the older


64


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


authors. Now, the view of Bottcher ( '69) is generally accepted. This large prominence vanishes during development, and instead of it a deep and wide furrow lined with low epithelium appears. These epithelial cells become peripherally higher and finally lean

TABLE 35

Radial distance between habenula perforata and the outer corner of the outer pillar cells at base on age (chart 14)- For the average values see the third column in table 9


AGE


BODY WEIGHT


TURNS OF TBE COCHLEA M


I


II


III


IV


Average


days


yrams







1


5


50


50


48


48


49


3


8


63


65


64


58


63


6


11


64


73


86


86


77


9


10


70


76


86


86


80


12


13


69


83


98


100


88


15


13


70


84


98


95


87


20


29


71


81


96


98


87


25


36


71


86


95


97


87


50


59


69


83


96


102


88


100


112


73


88


101


106


92


150


183


73


89


98


107


92


257


137


76


87


98


107


92


366


181


76


89


100


107


93


546


255


78


89


104


106


94


Ratios 1 12 days 1 20 " 1546 " 20546 "


1.4 1.4 1.6 1.1


1.7
1.6
1.8
1.1


1 -2.0

2.0
2.2


1 :2.1

2.0
2.2
1.1


1.8
1.8
1.9
1.1


100


80


60


40


AG^E DAYSH


O


25 5O 50 too 2OO 3OO 40O 500


Chart 14 The radial distance between the habenula perforata and the outer corner of the outer pillar cell at base, table 35, figure 2, distance 5.


GROWTH OF THE INNER EAR OF ALBINO RAT


65


on the inner supporting cells, which are termed ' Grenzzellen ' by Held ('02). The latter belong, of course, to this ridge, since the inner hair cell marks the outmost row in the ridge. The 'Grenzzellen' of Held, however, are different from other high cylindrical cells in the ridge, as they have a very intimate relation with the ' Phalangenzellen ' of Held, stand with their bases just

TABLE 36 Condensed

Ratios of the radial distance between the habentda perforata and the outer corner of the outer pillar cells at base on age




RATIOS BETWEEN TURNS


AVERAGE AGE


AVERAGE BODY




WEIGHT


I-II


i-in


I-IV


days


grams





1


5


1 :1.0


1 :1.0


1 :1.0


8


11


1.1


1.3


1.2


18


21


1.2


1.4


1.4


213


138


1.2


1.3


1.4


TABLE 37

Radial distance between habenula perforata and the outer corner of the outer pillar cells at base in n (Retzius)


RABBIT


CAT


Age


Basal


Middle


Apical


Average


Basal


Middle


Apical


Average



turn


turn


turn


turn


turn


turn


turn


turn


days










New-born


75


80


75


77


105


105


120


110


2


80


90


100


90








3








80


120





7


100


115


107


107


78


110


120


103


10


100


120


129


116








11








120


129


108


119


14


106


140


129


125








30








85


120


120


108


outward from the habenula perforata and serve to support the inner hair cell as Deiters' cells support the outer hair cells.

Thus the greater ridge includes in its prominence three kinds of cells, the high cylindrical cells, the 'Grenzzellen' of Held and the inner hair cell.

The greatest height of this ridge is not situated at a fixed point, but first lies somewhat outward from the middle part and


66


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


after the furrow appears, passes outward towards the inner supporting cells. Thus the greater ridge decreases in thickness from birth to nine days of age, then increases gradually to twenty days. After twenty-five days the values diminish again very slowly but continuously.

In table 38 (charts 15 and 16) are given the values of the greatest height of the greater epithelial ridge from the basilar membrane

TABLE 38

Greatest height of the greater epithelial ridge (resp. of the inner supporting cells)

on age (charts 15 and 16)



Bodv wcifitlitj


TURNS OF COCHLEA M




I


II


III


IV


Average height


days 1


grams 5


68


65


66


63


66


3


8


49


49


56


57


53


6


11


40


40


41


40


40


9


10


36


40


41


42


40


12


13


38


41


48


53


45


15


13


44


46


52


58


50


20


29


50


53


63


66


58


25


36


51


51


63


63


57


50


59


50


50


59


63


56


100


112


48


49


59


63


55


150


183


47


49


56


61


53


257


137


47


51


56


62


54


366


181


46


49


57


60


54


546


255


44


50


56


60


53


Ratios 1 9 days 1:0.6


12 20 " :1.3


12546 " :1.2


20546 " :0.9


1546 " :0.8


through the summit of the supporting cells, according to age. At the bottom of the last column is given the ratio at 1 to 9, 1 to 546, 12 to 20, 12 to 546, and 20 to 546 days of age.

The values in turn I are at birth the largest, but at three days the relation is reversed and remains so in the later age groups. Table 39 shows this relation from the condensed data.

Retzius ('84) gives in the rabbit and cat the following values (table 40).


GROWTH OF THE INNER EAR OF ALBINO RAT


67


In the rabbit the values decrease from birth till ten days, then increase; therefore, they agree in general with my results


50 40 30



25


50 50 10O 20O 30O 40O 500

Chart 15 The greatest height of the greater epithelial ridge (resp. of the inner supporting cells) table 38, figures 4 to 12.


70 44

60

5O 40 30


s


o


25


50


50 IOO 20O 3OO 4OO 500


Chart 16 The greatest height of the greater epithelial ridge (resp. of the inner supporting cells) arranged according to the turns of the cochlea, table 38, figures 4 to 12.

on the rat, while in the cat they diminish from birth till thirty days though irregularly.

The absolute values are greater for the rabbit than for the rat during the earlier stage, but afterwards they are similar.


68


In the cat the early data give values similar to those for the rat, but the later values are lower.

Bottcher's observations ('69) on the cat, calf, and sheep also give larger values than mine. In the cat the greater ridge has an average height of 75 [x and in both the others of 90 \L. Therefore, even in the same animal (cat) there are large differences in the data presented by different authors.

TABLE 39 Condensed

Ratois of the greatest height of the greater epithelial ridge (resp. of the inner sup- porting cells) according to the turns of the cochlea on age


Average age


Average body weight


RATIOS BETWEEB TURNS


I-II


i-in


I-IV


days


grams





1


5


1 :1.0


1 1.0


1 :0.9


8


11


1.0


1.1


1.2


18


21


1.1


1.2


1.3


213


138


1.0


1.2


1.3


TABLE 40


Greatest height of the greater epithelial ridge measured through the inner supporting

cells, in p. (Retzius)


RABBIT


CAT


Age

days


Basal turn


Middle turn


Apical turn


Average turn


Basal turn


Middle turn


Apical turn


Average turn


New-born


78


99


90


89


45


75


6S


63


2


60


90


90


80








3








40


84





7


51


68


63


61


40


54


63


52


10


36


54


56


49








11








50


58


66


58


14


51


51


51


51








30








30

.


45


45


40


Gottstein ('72) thinks that the greater epithelial ridge does not diminish its height for some time after birth, but through the outward development of the labium tympanicum, and in addition to this through the growth of the labium vestibulare, the sulcus spiralis internus arises. He does not give measurements.


GROWTH OF THE INNER EAR OF ALBINO RAT 69

His idea was strongly opposed by Bottcher ( 72) and my results are also opposed to Gottstein's view.

8. The radial distance between the labium vestibulare and the habenula perforata. The purpose of this measurement is to determine how the habenula perforata stands in relation to its surroundings during the development of the cochlea. The meas- urements of this distance is difficult. During the earlier stages, the labium vestibulare is quite undeveloped, especially in the upper turns. At birth we see on the inner surface of the greater epithelial ridge a small prominence under which the epithelial cells are short and pressed together so that the nuclei seem to be arranged in several rows (fig. 4). This appearance is due to the invasion of the subjacent connective tissue into the epithelium.

Thus the vestibular lip arises. We do not see a furrow at this time and cannot use the top of the furrow as a point for measuring as did Hensen ('63) in the ox and Bottcher ('69); in the em- bryo cat). To the measure the distance between the insertion of Reissner's membrane and the habenula perforata has no meaning for my purpose, because the length of the limbus laminae spiralis changes with age.

Thus I have measured the distance between the small epithelial prominence on the axial side of the greater ridge, corresponding to the edge of the labium vestibulare, and the habenula perforata.

In table 41 (charts 17 and 18) are given the -values of the radial distance between the labium vestibulare and the habenula perforata. At the foot of the last column are given the ratios from 1 to 546, 9 to 546, and 20 to 546 days. As we see, the values are a little bit smaller at the earlier stage. After nine days they are almost the same in every stage. The small differ- ences at the earlier and later stages are probably due to the retarded development of the labium vestibulare.

When we consider the values for this distance in each turn, it is evident that these increase from base to apex. In the con- densed table 42 this relation is shown.

Hensen ('63) finds that the distance from the top of the furrow to the habenula perforata is in the fetal calf and in the ox the


70


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


same, 255 [x. He considers the holes of the habenula as a ' punctum fixum. ' Bottcher ('69, 72) agrees with Hensen and gets in the cat embryo and the adult cat the following values (table 43).

TABLE 41

Radial distance between the labium veslibulare and the habenula perforata on age

(charts 17 and 18)


AGE


BODY WEIGHT


TURNS OP THE COCHLEA M


I


II


III


IV


Average


days


grams







1


5


100


108


120


130


115


3


8


80


110


130


137


114


6


11


82


105


135


137


115


9


10


83


108


137


145


118


12


13


80


102


139


148


117


15


13


82


107


144


157


122


20


29


84


106


146


153


122


25


36


82


105


147


150


121


50


59


82


104


137


147


118


100


112


80


103


151


154


122


150


183


80


107


141


144


118


257


137


83


105


143


150


120


366


181


79


105


135


149


117


546


255


79


105


143


150


119


Ratios 1 546 days

9546 " 20546 "


1.0 1.0 1.0


TABLE 42 Condensed


Ratios of the radial distance between the labium vestibulare and the habenula perforata according to turns of the cochlea




RATIOS BETWEEN TURNS


AVEKAGE AGE


WEIGHT


I-II


I-II I


I-IV


days


grams





1


5


1 1.1


1 1.2


1 1.3


5


10


1.3


1.6


1.8


141


93


1.3


1.7


1.8


Comparing the results of both Hensen and Bottcher with my own, the values obtained by Hensen are large, as would be expected in the larger animal. The cat and rat however, give similar values. We conclude, therefore, that broadly speak-


GROWTH OF THE INNER EAR OF ALBINO RAT


71


ing, the habenula perforata is to be considered as a 'punctum fix- urn, 'at least after birth.

9. The radial distance be'.ween the labium vestibulare and the inner edge of the head of the inner pillar cell To measure the


140


120


1OO


AGE DAYS-


25


50


50 1OO 2OO 3OO 40O 500

Chart 17 The radial distance between labium vestibulare and the habenula perforata, table 41, figure 10.


i cr\



































loO



































it





/



'-

































a



_






- v





/


^




.


-



















/





>










\




_



-












-


140



A


it









k














^ -


- !




_-











































/



































/

































12O








































































,*
































\t\f\





y











~


~




















1UO



1





































































































Qf\



1


o-


~j


^









(









^


a-


-












ou


































































































fj


i



g


/A-


f*f\





























|


2





Y


25


50


Chart 18 The radial distance between labium vestibulare and the habenula perforata according to the turns of the cochlea, table 41.

radial breadth from the labium vestibulare to the inner edge of the head of the inner pillar cell, I have used, at earlier stages, as in the preceding chapter, the same small prominence as an inner fixed point (fig. 4). In table 44 (chart 19) are given the values for this radial distance according to age. At the bottom of the last column are given the ratios from 1 to 9, 1 to 546


72


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


TABLE 43

Distance between labium vestibulare and habenula perforata in n (Bottcher)


PLACE OF


CAT EMBRYO 9 CM.


CAT EMBRYO 11 .5


CAT THREE DAYS


ADULT CAT


MEASUREMENT


LONG


CM. LONG


OLD



I turn


120


120


120


100


II turn


130


130


130


110


III turn


150


140


140


130


TABLE 44


Radial distance between the labium veslibulare and the inner edge of the head of the inner pillar cell on age (chart 19)


AGE


BODY WEIGHT


TURNS OF THE COCHLEA M


I


II


ill


IV


Average


days


grams







1


5


111


126


138


130


126


3


8


84


118


150


170


131


6


11


88


119


159


180


136


9


10


94


131


168


179


143


12


13


69


97


138


156


115


15


13!


",' 66


103


137


149


114


20


29


66


103


137


148


114


25


36


65


100


136


148


112


50


59


61


98


129


144


108


100


112


64


99


139


153


114


150


183


60


99


129


143


108


257


137


67


100


134


149


113


366


181


60


102


130


151


111


546


255


55 :..


99


128


143


106


Ratios 1 9 days

1546 " 12546 "


1.1

0.8 0.9


TABLE 45 Condensed


Ratios of the radial distance between the habenula perforata and the inner edge of

the head of the inner pillar cell according to the turns of

the cochlea on age




KATIOS BETWEEN TURNS


AVERAGE AGE


WEIGHT







I-II


I-HI


I-IV


days


grams





1


5


1 1.1


1 \.9


1 1.2


6


10


1.4


1.8


2.0


154


102


1.5


2.1


2.3


GROWTH OF THE INNER EAR OF ALBINO RAT


73


and 12 to 546 days of age. As the table shows, the values in- crease in general from birth to nine days; therefore, the surface of the greater epithelial thickening from the labium vestibulare to its outer boundary becomes, during the earlier stage, wider and wider, then decreases sharply, and after that continuously but slowly. This sudden diminishing of the distance has a very intimate relation with the change in the form of the papilla spiralis at this stage of development.

This point I will discuss later.

That the values increase from the base to the apex first rapidly and later less rapidly, is also to be seen here. Table 45 shows this relation clearly. It is remarkable, however, that the ratio becomes


140


12O


1OO


AGE DAYS'


25


50 50 1OO 2OO 300 400 50O

Chart 19 The radial distance between the labium vestibulare and the inner edge of the head of the inner pillar cell, table 44.

at each turn larger with age, although the absolute value is after nine days generally smaller than at the preceding age. Therefore, we see that the diminution of the distance after nine days is largest in the basal turn and smallest in the apical. Hensen ('63) asserts that there is a movement axialward of the organ of Corti (resp. the head of the pillar cell), but gives no measurements. Neither Bottcher nor Retzius measured this distance. Prentiss ('13, page 445) states that "the distance between the inner angle of the cochlea and the pillar cells, two definite points, may be measured with considerable accuracy and shows no important change in the position of the spiral organ from the 13 cm. to the 18.5 cm. stage, nor later in the new born animal" (pig) But he also does not record his meas- urements.


74


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


Hardesty ('15, p. 54) says "that the space occupied by the width of the greater epithelial ridge increases throughout the coils of the cochlea up to pigs of 15 to 16 cm., and thereafter it begins to decrease very perceptibly." He measured the width from the membrana propria of the epithelium of the greater ridge, at its most axial extension under Huschke's teeth, to the apical end of the inner hair cell of the spiral organ. " The

TABLE 46

Vertical distance from the membrana basilaris to the surface of the pillar cells on

age (chart 20}




TURNS OF THE COCHLEA M


AGE


BODY WEIGHT





I


II


ill


IV


Average


days


grams







1


5


35


36


39


36


37


3


8


30


29


29


29


29


6


11


29


32


31


29


30


9


10


32


33


35


36


34


12


13


41


45


50


52


47


15


13


44


48


53


57


51


20


29


53


57


67


71


62


25


36


55


56


66


68


61


50


59


53


55


67


68


61


100


112


53


54


64


67


60


150


183


52


54


63


66


59


257


137


53


56


63


69


60


366


181


51


56


66


67


60


546


255


52


55


62


66


59


Ratios 1 12 days 1-1.3


1 20 " 1.7


1546 " 1.6


12546 " 13


20546 " 1.0


method of measurement differs from mine, so the results cannot be compared directly. While the distance in the rat increases to nine days of age, that in the pig decreases perceptibly in fetuses more than 16 cm. long.

According to Hardesty ('15, p. 55). "the decrease in the I and III half turns may be as much as one-third of the width of the greater ridge when at its maximum size and activity. " And "after the tectorial membrane is about completely produced,


GROWTH OF THE INNER EAR OF ALBINO RAT


75


and while the spiral organ is enlarging, the inner hair cells, and therefore the organ, may be moved in the apical coil of the cochlea axialward a distance of about half the maximum width

of the greater epithelial ridge, "

The differences of the values in the rat at 9 and 546 days are in the basal and apical turn about the same, 39 and 36 n, res- pectively (table 44). Thus while the inner edge of the inner pillar cell approaches at 546 days in the basal turn by as much as 41 per cent of the distance present at nine days, that in the


80


60


40


20


AGE.qAYS-


25 50 5Q 1QO 2OO 300 4OO 5OO

Chart 20 The vertical distance from the membrana basilaris to the surface of the pillar cells, table 46, figure 1, 1-1.

apex moves only 20 per cent inward in old age. This result is the reverse of that obtained in the pig by Hardesty. The reason for this contradiction I will discuss later.

10. The vertical distance from the membrane basilaris to the summit of the pillar cells. The method of getting the vertical distance from the membrana basilaris to the surface of the pillar cells is shown in figure 1, line 1-1. In table 46 (chart 20) are given the values thus obtained. At the foot of the last column are given the ratios of this distance at 1 to 12, 1 to 20, 1 to 546, 12 to 546, and 20 to 546 days. The average value is relatively large at birth, it diminishes at three days, then increases more rapidly to twenty days. After this it decreases very slowly. The maximum height of the arch of Corti is at twenty days of


76


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


age. Comparing the values for the height in each turn, we find that from nine days they increase from the basal to the apical turn. This relation can be easily seen in table 47.

Retzius ( '84) gives in the rabbit and cat the following values (table 48).


TABLE 47 Condensed


Ratios of the vertical distance from the membrana basilaris to the surface of the pillar cells according to the turns of the cochlea




RATIOS BETWEEN TURNS



AVERAGE BODY



AVERAGE AGE


WEIGHT







I-II


i-ni


I-IV


days


grams





1


5


1 :1.0


1 : 1.1


1 : 1.0


1


11


1.1


1.1


1.1


18


21


1.1


1.2


1.3


213


138


1.0


1.2


1.3


TABLE 48 Vertical distance from the membrana basilaris to the summit of the pillar cells


BABBIT


CAT


Age


Basal

turn


Middle turn


Apical turn


Average


Basal turn


Middle turn


Apical turn


Average


days










New-born


45


70


61


59


45


60


48


51


2


45


69


40


51








3








39


60





7


46


60


60


55


45


47


50


44


10


45


69


69


61








11






JK


50


60


42


51


14


45


57


66


56








30






' }'


33


51


57


47


Table 48 shows that the height of the arch of Corti in the rabbit approximates that in the rat, though there are considerable differences in the earlier stages. In the former the arch of Corti develops after: birth only a little, and is therefore more pre- cocious than in the rat. In the cat the same relation is to be seen, but the absolute values in the latter animal are smaller than in either the rabbit or the rat.


GROWTH OF THE INNER EAR OF ALBINO RAT 77

11. The greatest height of the tunnel of Corti. Some authors have reported in several animals the appearance of the tunnel of Corti just after birth, or even in later intrauterine life. In the rat, however, it first appears through all the turns after the ninth day. Sometimes we see it at nine days in the lower turn, though not yet in the upper. The method of measuring the height is shown in figure 1, line 1-1'. Table 49 (charts 21 and 22) gives the values for the greatest height of the tunnel of Corti. At the foot of the last column are given the ratios from 12 to 25, 12 to 546, and 25 to 546 days.

As the table shows, the space appears in all the turns at twelve days and has considerable height. This increases to twenty-five days, than decreases very slowly. This increase and decrease correspond to the changes in the distance of the summit of the pillar cells from the basilar membrane.

When we consider the height in each coil of the cochlea, we find the value increases from the base to the apex, first rapidly then slowly. In table 50 this relation is clearly shown.

Retzius ('84) gives the values for the adult rabbit, man and cat (one month) as follows (table 51).

According to this table, the average height is in the adult man, cat, and rabbit somewhat less than in the rat.

12. The height of the papilla spiralis at the third series of the outer hair cells. The measurements were taken along the line 2-2 shown in figure 1. The growth of this vertical height depends not only upon the increase of the length of the corre- sponding outer hair cell, but chiefly upon the development of the Deiters' cells, especially of the outermost row, and of the sustentacular cells of Hensen.

In table 52 (charts 23 and 24) are given the values for this vertical height of the papilla spiralis at the third series of the outer hair cells according to age. At the bottom of the last column are the ratios at 1 to 12, 1 to 20, 1 to 546, and 20 to 546 days. The heights decrease at three days, but increase from nine to twelve days very rapidly, nearly doubling their minimal values, and reach a maximum at twenty days. After that time they decrease very gradually to the end of the record. There-


78


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


TABLE 49 Greatest height of the tunnel of Corti on age (charts 21 and 22}


AGE


BODY WEIGHT


TURNS OP THE COCHLEA M


I


II


ill


IV


Average


days


grams







1


5









3


8









6


11









9 1


10









12


13


29


33


39


37


35


15


13


31


34


42


46


38


20


29


37


42


52


56


47


25


36


39


41


54


56


48


50


59


38


41


53


57


47


100


112


38


43


51


56


47


150


183


37


41


49


54


45-


257


137


38


43


51


56


47


366


181


37


41


52


53


46


546


255


36


39


48


53


44


Ratios 12 25 days 12546 " 25546 "


1.4 1.3 0.9


1 In one case nine days old which could hear the space was found through all the turns of the cochlea.

TABLE 50 Condensed

Ratios of the greatest height of the tunnel of Corti according to the turns of the

cochlea on age




, RATIOS BETWEEN TURNS



AVERAGE BOOT



AVERAGE AGE


WEIGHT







I-II


i-ni


I-IV


days


grams





12


13


1 : 1.1


1 1.3


1 1.3


18


21


1.1


1.4


1.5


213


138


1.1


1.3


1.4


TABLE 51 The greatest height of the tunnel of Corti in n (Retzius)


RABBIT


CAT (one month)


MAN


Basal


Middle


Apical


Aver- age


Basal


Middle


Apical


Aver- age


Basal


Middle


Apical


Aver- age


30


39


36


35


18


37


36


30


28


45


49


41


GROWTH OF THE INNER EAR OF ZLBINO RAT


79


fore, the difference between the ratios at 1 to 20 and 1 to 546 days is very small.

At twelve days and after, the values for the height increase in passing from the base to the apex, at first rapidly, then more slowly. In the earlier stages this relation is obscure or reversed.


60 40

20 n










































































































































1


^











JS.























/

























x
































































































































































































































G


E


c


A


Y5-
































25


50


5O 10O 20O 300 400 5OO


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60


40





































































































/(


^'






'




-


__ (








_



,



-












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-









-



-


-


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1











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A


>/c





























u





Y






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5





5



5<


D


II


~\c J\.


)



2(


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)



3(


DC


)


4


4C


)0




5C


)0





Chart 22 The greatest height of the tunnel of Corti, according to the turns of the cochlea, table 49. .

In the condensed table 53 are given the ratios in each turn. While the ratio of each turn before eight days is about 1:1.1, and between turns I and II remains constant in the later age, that for I to III and I to IV is at 18 and 213 days decidedly larger. Therefore, the increase of the height is most marked in the III and IV turn, as shown in chart 24.


TABLE 52

Height of the papilla spiralis at the third series of outer hair cells on age (charts 23 and 24)


AGE


BODY WEIGHT


TURNS OF THE COCHLEA M


I


II


III


IV


Average


days


grams







1


5


35


35


39


28


34


3


8


22


23


25


26


24


6


11


25


24


25


23


24


9


10


28


28


27


28


28


12


13


40


49


54


56


50


15


13


46


53


65


66


58


20


29


56


61


76


81


69


25


36


56


61


76


78


68


50


59


53


59


78


80


68


100


112


54


59


74


79


67


150


183


55


57


75


77


66


257


137


54


59


74


81


67


366


181


5?


58


75


78


66


546


255


52


58


72


75


64


Ratios 1 12 days 1 1.5 1 20 " 2.0


1546 " 1.9


20546 " 0.9 TABLE 53 Condensed


Ratios of the height of the papilla spiralis at the third series of outer hair cells according to the turns of the cochlea on age


AVERAGE AGE


AVERAGE BODY WEIGHT


BATIOS BETWEEN TURNS


I-II


i-ni


I-IV


days


grams





1


5


1 :1.0


1 :1.1


1 0.8


8


11


1.1


1.1


1.1


18


21


1.1


1.4


1.5


213


138


1.1


1.4


1.5


TABLE 54 Height of the papilla spiralis at the third scries of outer hair cells in n (Retzius)


BABBIT


CAT


AGE


Basal turn


Middle turn


Apical turn


Average


Basal turn


Middle turn


Apical turn


Average


days










New-born


48


70


60


59


45


60


45


50


2


45


70


54


56








3








40


58





7


54


69


66


63


42


5<


48


49


10


42


86


84


71








11








60


72


42


58


14


60


87


90


79








30








36


57


70


54


80


GROWTH OF THE INNER EAR OF ALBINO RAT


81


Retzius ('84) finds in the rabbit and cat the [values for this height given in (table 54).

Comparing these average numbers with mine, it appears that the height in the rabbit is greater, and in the cat smaller than


u

70 5O 30 10


k


AGE


o


25 5O 50 |OO 2OO 3OO 40O 5OO


Chart 23 The height of the papilla spiralis at the third series of the outer hair cells, table 52, figure 1, 2-2.


90


70


50


30


10



AGE DA.YS-


O


25


50


5O 1OO 2OO 3OO 4OO 5OO


Chart 24 The height of the papilla spiralis at the third series of the outer hair cells, according to the turns of the cochlea, table 52.

in the rat. In both animals the values increase rapidly at ten to eleven days of age, as in the albino rat, but the height in these animals is at the earlier stage almost twice as large as in the rat. Hardesty ('15) measured the thickness of the organ of Corti in


82


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


the pig in a somewhat different way, using the vertical line from the basilar membrane proper through the m'ddle of the outer hair cell to the surface of the organ, and found the increase in thickness to take place most rapidly at the stages before full term, though it seems to continue after birth. I have not made cor-

TABLE 55

Greatest height of Hensen's supporting cells on age (chart 25)


AGE


BODY WEIGHT


TURNS OP THE COCHLEA M


1


II


III


IV


Average


days


grams







I


5


36


36


38


31


35


3


8


18


21


21


24


21


6


11


21


20


21


18


20


9


10


20


23


23


24


23


12


13


40


49


56


58


51


15


13


44


56


69


72


60


20


29


64


64


86


87


75


25


36


69


71


84


86


78


50


59


71


74


87


89


81


100


112


77


. 78


87


89


83


150


183


76


77


<3


93-


85-


257


137


81


83


89


89


86


366


181


82


83


89


91


86


546


255


79


79


92


93


86


Ratios 1 6 days

1 12

1 20

1546

6 12

6 20

6546 12 20 12546 20546


0.6 1.5 2.1 2.5 2.6 3.8 4.3 1.5 1.7 1.1


responding studies on the rat. In the latter animal, however, the rapid increase usually appears at twelve days of age, when the animal as a rule first responds to auditory stimuli, and thus we have a correlation between the development of the organ and the beginning of the function, which will be discussed later. In the case of one rat that could hear at nine days this change had already occurred.


GROWTH OF THE INNER EAR OF ALBINO RAT


83


13. The greatest height of Hensen's supporting cells. The older authors (Kolliker and others) thought that the arch of Corti marks the highest point of the papilla which slopes from this point gradually outward to the cells of the zona pectinata. Against this erroneous idea Hensen ('63) first published obser- vations showing that the highest point is in the papilla which ascends laterally from the outer hair cells, and then slopes abruptly and passes over to the cells of the sulcus spiralis externus. We term this prominence Hensen's prominence and the cells, Hensen's supporting cells. The measurements of the height of


90

M

70

50 30 \c\



















































































































.-<


-
























s


l
































1


































/


































1

































/

































I'

































i

































1

































|
































\


j
































\


1
































\


jj


























































GE

i




T





























25 50 50 100 200 300 400 50O

Chart 25 The greatest height of Hensen's supporting cells, table 55.

these cells were made along 3 3 in figure 1. Table 55 (chart 25) shows the values for the greatest vertical height of these supporting cells according to age. At the foot of the last column are given the ratios from 1 to 6, 1 to 12, 1 to 20, 1 to 546, 6 to 12, 6 to 20, 6 to 546, 12 to 20, 12 to 546, and 20 to 546 days. The values diminish at the earlier stage from birth to six or nine days. At twelve days they increase suddenly, more than doubling. After that they increase to old age, rapidly up to twenty days and then slowly. Here also the height increases from the base to the apex, the most marked increase occurring between turns II and III. In table 56 this relation is clearly shown. Retzius ('84) gets values of this height in the rabbit and cat as follows (table 57).


84 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON

In both the rabbit and the cat the height increases at ten to eleven days very considerably, as it does in the rat. Only there is a large difference in the absolute values for the three animals, these being largest in the rabbit and smallest in the cat. The final average values in the cat are nearly the same as those in the rat at the same age.

Kolmer ('07) finds in the calf the value in the highest point of the organ of Corti in the region of the innermost Hensen's cells as follows:

In the basal turn, 84 [A

In the second turn, 90 JJL

In the third turn, 105 [JL

Average, 93 [i.

Hensen ('63) gives in man the average height of the papilla as 90 (JL in the hamulus and 60 [j. in the radix. Thus the height of Hensen's cells is different in different animals.

When we consider the growth in the height of Hensen's cells we can picture the change of the form in the papilla spiralis. As shown already, the height of the pillar cells is largest at the earlier stage, when the papilla has its highest point at the summit of the arch of Corti, and slopes downward to the Hensen's cells. But at twelve days the form is reversed, and the highest point is in Hensen's prominence from which the surface slopes inward more or less steeply to the surface of the pillar cells and the inner supporting cells. Thus the surface of the papilla does not run parallel to the basilar membrane, but makes with it a sharp angle opening outward. This angle has been measured.

14- The angle subtended by the extension of the surface of the lamina relicularis with the extended plane of the membrana basilaris. As just stated, the lamina reticularis after the earlier stages is not parallel to the membrana basilaris, but forms an angle with it. The measurements of this angle , were taken as shown in lines 4~4' i n figure 1. In table 58 (chart 26) are given the values for the angle in degrees. Before nine days there is no appreciable angle. From twelve to twenty days the angle increases rather rapidly, and after twenty days continuously but slowly. The ratio at the bottom of the last column shows this clearly.


GROWTH OF THE INNER EAR OF ALBINO RAT


85


Comparing the values of the angle in each turn according to age, there is no clear evidence that it increases from base to apex, though it tends to be largest in turn III and next largest in turn II. The condensed table 59 shows these relations. Retzius ( ; 84) finds this angle in the rabbit and cat to be as in table 60.

TABLE 56 Condensed

Ratios of the greatest height of Hensen's supporting cells according to the turns of

the cochlea




RATIOS BETWEEN SUCCESSIVE TURNS


AVERAGE AGE


AVERAGE BODY




WEIGHT


1





I-II


I-III


I-IV


days


grams





1


5


1 1.0


1 1.1


1 0.9


8


11


1.1


1.2


1.2


18


21


1.1


1.4


1.5


213


138


1.0


1.2


1.2


TABLE 57 Greatest height of Hensen's supporting cells in M (Retzius)


RABBIT


CAT


Age Days


Basal turn


Middle


Apical


Average


Basal


Middle


Apical


Aver- age


Xew-born


38?


60?


50?


49?


45


50


39


45


2


55?


60?











3








39


54





7


48


81


67


65


57


50


40


49


10


105


125


105


112








11








75


78


45


66


14



150


120









30








50


69


95


71


Retzius also finds in man in the basal turn 25, in the middle 35, and in the apical 23. Thus the angle always increases with age, but has different absolute values in different mammals and always tends to be greater in the middle turns.

15. Lengths of the inner and outer pillar cells. The measure- ments of length were taken as shown by lines 1-1, and 2-2 as in figure 2. This does not give the total length, but the length from the base to the point, just below the joint. As is well


86


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


TABLE 58

Angle of the lamina reticularis with the plane of Ihe membrana basilaris in

degrees, 6 (chart 26}





TURNS OF THE COCHLEA DEGREES


AGE


BODY WEIGHT






I









II


III


IV


Average


days


grams







1


5









3


8









6


11









9


10









12


13


7


12


13


9


10


15


13


11


14


13


13


13


20


29


15


13


11


11


13


25


36


14


14


13


13


14


50


59


15


15


17


11


15


100


112


15


14


16


14


15


150


183


15


15


19


17


17


257


137


13


15


18


17


16


366


181


16


15


16


16


16


546


255


16


16


17


17


17


Vertical averages



13.7


14.3


15.3


13.8



Ratios 12 20 days 1 : 1.3

12546 " :1.7

TABLE 59 Condensed

Ratios of the angle of the lamina reticularis with the plane of the membrana basilaris according to the turns of the cochlea





RATIOS BETWEEN TURNS


AVERAGE AGE


AVERVGE BODY WEIGHT


I-II



I-II I


I- IV


days 12


grams 13


1 1.7


1 1.9


1 : 1.3


18


21


1.0


0.9


0.9


213


138


1.0


1.2


1.0


TABLE 60

Angle of the lamina reticutaris with the plane of the membrana basilaris in degrees

(Retzius)


Age


Basal turn


Middle turn


Apical turn


Average


Basal turn


Middle turn


Apical turn


Average


days










New-born



5?


8?






5? 8?



2














3









5? 8?





7


17


19


11



5


5


10



10


20


30


23


24








11








20


1020





14


25


50


45


40








30








18


23


20


20


GROWTH OF THE INNER EAR OF ALBINO RAT


87


known, the inner and outer pillar cells when mature show a more or less S-shaped curvature, though they are straighter in the earlier stages. Thus the length as measured in the adult cochlea is somewhat smaller than the natural lengths.


DEGREES 18


15


12




25


50


5O 1OO 20O 300 40O 500


Chart 26 The angle subtended by the extension of the lamina relicularis with the extended plane of the membrana basilaris, in degrees, table 58, fieure 1 4-4', 9-

In table 61 (charts 27 to 32) is given the values for the lengths of the inner and outer pillar cells according to age. At first we shall consider the average values for the length of the inner and outer pillar cells taken together. This length diminishes at three days. From three to twelve days it increases rapidly,


88


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


and from twelve to twenty days more slowly. After twenty days it decreases a little. The ratios at the bottom of the last column show these relations. The familiar fact, that the length increases from the base to the apex is clearly shown in chart 28.


TABLE 61


Lengths of the inner and outer pillar cells (without head) measured from the footplate on the membrana basilaris to the point directly below the junction (charts 27 to 32)


AOE


BODY WEIGHT


INNER PILLAR


OUTER PILLAR


Com- bined Average


Turns of the cochlea M


Turns of the cochlea M


I


II


ill


IV


Average


I


II ill


IV


Average


days


gms













1


5


28


29


29


29


29


24


27


27


26


26


28


3


8


26


23


26


23


25


19


20


20


21


20


23


6


11


35


36


36


37


36


21


26


27


26


25


31


9


10


35


39


41


40


39


26


26


29


29


28


34


12


13


33


38


44


44


40


46


59


72


72


62


51


15


13


34


38


48


51


43


44


59


74


78


64


54


20


29


43


47


56


60


52


56


65


79


83


71


62


25


36


43


47


56


60


52


53


64


80


84


70


61


50


59


42


44


55


61


51


52


64


79


84


70


  • 61


100


112


42


44


53


58


49


52


62


79


84


69


59


150


183


41


43


54


59


49


51


64


76


85


69


59


257


137


40


44


53


60


49


53


64


75


85


69


59


366


181


39


45


53


59


48


50


64


78


83


69


59


546


255


41


44


53


58


49


49


64


78


83


69


59


Ratios 1- 12 days




1 1.4






1 :2.4


1 : 1.8


1- 20 "




1.8






2.7


2.2


1-546 "




1.7






2.7


2.1


20-546 "




0.9






1.0


1.0


When we calculate the average values of the inner and outer pillar cells from Retzius table ('84), we get the following (table 62). .

TABLE 62

Combined lengths of the inner and outer pillars from the foot plate to a point directly below the junction in n (Retzius)


RABBIT (adult)


CAT (adult)


MAN (adult)


Basal turn


Middle turn


Apical turn


Aver- age turn


Basal turn


Middle turn


Apical turn


Aver- age


Basal turn


Middle turn


Apical turn


Aver- age


66


85


78


76


55


75


73


67


55


84


87


75


GROWTH OF THE INNER EAR OF ALBINO RAT


89


70


50


30


10





25


50


5O 1OO 2OO 300 4OO 5OO


Chart 27 The length of inner and outer pillar cells combined, without head, measured from the foot plate on the membrana basilaris to the point directly below the junction, table 61, figure 2, /-/, 2-2.


80




w.q A re




25 50 50 JOO 200 300 4OO 5OO


Chart 28 The length of inner and outer pillar cells combined, without head, measured from the foot plate on the membrana basilaris to the point directly below the junction, according to the turns of the cochlea, table 61.


,u 50

30

in










































































































































































s

































r -'


































































J






























































































GE


D


A































TO




25


5O


2OO


5(X)


Chart 29 The length of inner pillar cell without head, table 61, figure 2, 1-1.


90 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON

As table 62 shows, the values in these mammals are larger than those in the albino rat a result which fits with our previous observations.

When we consider the length of the inner pillar cells alone, we see that the values (chart 29) here also increases from three days to twenty days, but not so largely as in the combined values of the inner and outer pillar cells. After twenty days the values for the inner pillar cells decrease slightly. This relation is shown by the ratios at the bottom of the corresponding column. That the increase progresses from the base to the apex, being most marked in turn III, is illustrated in chart 30. The condensed table 63 shows those relations also. The one-day-old rat is an exception.

We turn now to the growth in the length of the outer pillar cells. As we see in table 61 (chart 31), the length of the outer pillar cell does not increase so much from one to nine days as the inner pillar cell did. At twelve days, however, the increase in length is very marked, that is, 2.2 times as much as at nine days.

After the outer pillar cell reaches its maximum at twenty days, it decreases only slightly with advancing age. The ratios at the bottom of the corresponding column show this relation clearly. The length increases from base to apex, though this relation is not well established until twelve days, as shown in table 61 and chart 32. The ratios of the outer pillar cells ac- cording to the turns of the cochlea are shown in table 64.

The inner and outer pillar cells show marked differences in their growth. While at the earlier ages the length of the inner is greater than that of the outer, yet after twelve days this relation is reversed. Moreover, from nine to twelve days the growth is gradual in the inner pillar cells, but rapid in the outer. The condensed table 65 shows the values for the length of the inner and outer pillar cells separately. In the last column are given the ratios between them.

In the accompanying table 66 I have compared the values obtained in the rat with those given by other authors.

As table 66 shows, the absolute values differ in various animals. However, the ratios between the values for the inner and outer


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ft


p


IT

L


P L


ft


vcj-


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o


25


50 50 10O 200 3OO 4OO 50O

Chart 30 The length of the inner pillar cell without head, according to the turns of the cochlea, table 61.


80

M 60

40 20

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1

































1

































































































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,






















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.'"1
































\





























































































































AGE

i i


DAY
































25


50


5O 1OO 200 300 4OO 50O

Chart 31 The length of outer pillar cells without head, table 61, figure 2,


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^






















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~


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~



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n


t *
































oo



































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A


k/C


n






























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1OT




25 50 50 1OO -OO 3OO 4OO 5OO


Chart 32 The length of outer pillar cells without head, according to the turns of the cochlea, table 61.

91


92


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


TABLE 63 Condensed Ratios of the length of the inner pillar cells according to the turns of the cochlea


AVERAGE AGE


AVERAGE BOOT WEIGHT


RATIOS BETWEEN TURNS


I-II


I-II I


I-IV


days 1


grams 5


1 1.0


1 1.0


1 1.0


8


11


1.1


1.2


1.1


18


21


1.1


1.3


1.4


213


138


1.1


1.3


1.4


TABLE 64 Condensed Ratios of the length of the outer pillar cells according to the turns of the cochlea


AVERAGE AGE


AVERAGE BODY WEIGHT


RATIOS


BETWEEN TURNS





I-II


I-II I


I- IV


days 1


grams 5


1 : 1.1


1 1.1


1 1.0


8


11


1.2


1.3


1.3


18


21


1.2


1.5


1.6


213


138


1.3


1.5


1.6


TABLE 65 Condensed

Comparison of the average length of the inner and outer pillar-cellswithout

head.




AVERAGE LENGTH OF PILLAR CELLS



AVERAGE AGE


AVERAGE BODY


WITHOUT HEAD


RATIOS OF INNER



\V V T ( ' H T



TO OUTER




Inner


Outer



days


grams





1


5


29


26


1 :1.0


8


11


35


34


1.0


18


21


48


68


1.4


213


13S


50


69.


1.4


pillar cells are smallest in man and in the rat and alike in the other two forms, Retzius ('84). Hensen ('63) states that in the base of the human cochlea both pillar cells are equally long. Later, Pritchard ('78) supported this observation. In the literature, however, no one except these two authors report the inner and outer pillar cells in the base of the adult cochlea as equal in length, but the inner is always stated to be shorter than the outer. We may therefore say that most authors agree that the inner pillar cells are at earlier stages longer than the outer, then they become equal, and finally the outer surpass the inner.


GROWTH OF THE INNER EAR OF ALfcINO RAT


93


TABLE 66

Lengths of inner and outer pillars in several mammals according to different authors.

Measurements in n


INNER PILLAR


OUTER PILLAR


Authors


Animals


Basal turn


Mid- dle


Apical



Av.


B.


M.


A.



Av.


Ratio


Corti


Mam- mals


30


30


34


31


45- 49


54-

58


69


57


1:1.8


Hen- sen


Man


48



86 (Hamul-

us)


48




98 (Hamul- us)



Ret-

zius

Wada


Rabbit


56


60


60


59


75


110


95


93


l.


Cat


41


54


57


51


68 62


95


89


84


1.6


Man


48


68


70


62


100


103


88


l.t


Albino rat after 20 days


I 41


II 45


III

54


IV

59


50


I 52


II 64


III

78


IV

84


70


-.1.4


16. Inner and outer hair cells. For a long time the inner and the outer hair cells have been regarded as the most important elements in the papilla spiralis. As these sense cells have a delicate histological structure which is readily altered, the systematic study of their growth, especially after the appearance of hearing, is a difficult matter. Though there are some observations on the length of these cells, detailed studies on their growth have not been made heretofore. I have therefore endeavored to follow the changes of their size during the postnatal period. It is first necessary to determine the form of these cells. They are generally described as cylindrical, but this description is inexact. Moreover, the inner and outer hair cells are somewhat different in shape. The former has on the surface a large oval terminal disk, which is wide hi the spiral and narrow in the radial direction. This narrows downwards to a thinner neck which expands into the broader body and terminates in a more or less round but somewhat pointed irregular end.


94


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


1600

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5O 100 2OO 300 4OO 5OO


Chart 33 The weighted volume of inner and outer hair cells combined, and of their nuclei in cubic micra, tables 67 and 69.

- Weighted volume of inner and outer hair cells combined. Weighted volume of nuclei of inner and outer hair cells combined.

The outer hair cells have a much more cylindrical form, their upper terminal disk is not so wide and not round, but hexagonal. They become a bit thin in the neck, then wide in the body. Their lower end is rounded. In order, however, to determine the cell volume, the cell form has been taken as that of a cylinder. For computation, the average of the diameters measured in three places, the end disk, neck, and cell body, was taken as the diameter and the length of the cell as the length of the cylinder. From these data the volume of the cylinder was computed.


GROWTH OF THE INNER EAR OF ALBINO RAT


95


In table 67 are given the values for the volume of the cell bodies in the (1) inner and (3) outer hair cells separately and the weighted volume of both cells (in the radial section of the rat cochlea we see one row of inner and three rows of outer hair cells), according to age.

TABLE 67

Average volumes of the inner and outer hair cells in cubic micro (charts 33 to 37)


AGE



INNER HAIR CELL


OUTER HAIR CELL



BODY WGHt


Tu

I


rns of II


the o III


achlea IV


fit Average


T I


urns o II


f the ( III


iwlilr;

IV


l M 3 Average


WEIOHTD AVERAGE VOLUME


days 1


gms 5


1255


982


832


631


925


641


626


505


359


533


631


3 6 ' 9 12 15 20


8 11 10 13 13 29


1457 1374 1451 1553 1598 1627


1367 1451 1734 1812 1618 1764


1206 1549 1994 1910 1902 1972


913 1221 2013 2157 2128 2189


1236 1399 1798 1858 1812 1888


767 1047 914 818 815 894


928 967 1308 1210 1178 1215


867 1053 1459 1602 1595 1606


571 800 14^8 1499 1559 1960


783 967 1277 1282 1287 1419


896 1075 1407 1426 1418 1536 1293


Av. 11


14


1510


1624


1756


1770


1665


876


1134


1364


1303


1169


25 50 100 150 257 366 546


36 59 112 183 137 181 255


1540 1497 1353 1362 1345 1290 1266


1655 1611 1550 1497 1524 1561 1486


1909 1821 1744 1683 1738 1817 1772


1995 1924 2018 1917 1976 2297 2257


1775 1713 1666 1615 1646 1741 1695


834 805 837 832 873 893 831


1243 1204 1306 1150 1230 1239 1336


1539 1580 1510 1803 1555 1651 1650


1702 1906 1737 1917 1927 1844 1839


1330 1374 1348 1426 1396 1407 1414


1441 1459 1428 1473 1459 1491 1484


Av. 213


138


1379


1555


1783


2055


1693


844


1244


1613


1839


1385


1462


Ratios 1- 12 days 1- 20 " 1-546 " 20-546 " 1- 11 " 11-213 "


1 :2.0

2.0

0^9



1 :2.4

2.7
2.7
2!2


1 :2.3

2.4
2.4
0.9
2.0


At first we shall consider the weighted volume for the cell bodies of the inner and outer hair cells combined (chart 33). As table 67 shows, the volume increases continuously to the full size at twenty days. From one to twelve days the increase is rapid, and after that the volumes are about the same, though somewhat fluctuating. The ratios show this relation clearly.


96


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


Condensing all age groups into three (averages in table -67), then the relation changes somewhat. From one to eleven days the volume increases more than 100 per cent, while from eleven to 213 days it increases only 13 per cent.


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Chart 34 The volume of inner hair cells and of their nuclei, tables 67 and 69.

Volume of inner hair cells. Volume of nuclei of inner hair cells.

The data for the growth of the nuclei of the inner and outer hair cells are presented in tables 68 and 69. The weighted values for the diameters of the nuclei (table 68) are large at the earlier stages, but from twelve days decrease gradually till


GROWTH OF THE INNER EAR OF ALBINO RAT


97


old age. In the three condensed age groups (averages) we see the decrease of the values from birth till old age. In table 69 are given the values for the volumes of the nuclei, calculated as spheres (chart 33).


M*


1600


10OO


600


400


V


AGEjDAYS-


25


50 50


2OO 3OO 400 500


Chart 35 The volume of inner hair cells, according to the turns of the cochlea, table 67.


98


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


The weighted values for the volumes of the inner and outer hair cells in each turn are given in [A 3 table 70. At the bottom of each column is given the ratio from 1 to 12, 1 to 20, 1 to 546, and 20 to 546 days of age. While the volume at birth is largest in turn I and smallest in turn IV, that in turn III is largest at


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Chart 36 The volume of outer hair cells and of their nuclei, in cubic micra, tables 67 and 69.

Volume of outer hair cells.

._. Volume of nuclei of outer hair cells.

six days. After nine days the volume increases always from base to apex.

Comparing the weighted vo'ume in each turn according to age, we find that the rate of increase in volume is smallest in turn I (1.3 to 1.2) and largest in turn IV (3.9 to 4.6) (table 70).

In table 72 are given the weighted values for the diameters of the nuclei of the inner and outer hair cells in each turn. They


GROWTH OF THE INNER EAR OF ALBINO RAT


99


increase and then decrease during the first twelve days. The rate of decrease is largest in turn I, and smallest in turn IV, as the ratios at the bottom of each column show. That the diameters at


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Chart 37 The volume of outer hair cells, according to the turns of the cochlea, table 67.

the later ages have about the same value in each turn, or are a little larger in the upper than in the lower turn, is to be seen in table 73.


TABLE 68 Mean diameters of the nuclei of the inner and outer hair cells in M




DIAMETERS NUCLEI OF THE


DIAMETERS NUCLEI OF THE





INNER HAIR CELLS


OUTER HAIR CELLS







WEIGHT-


AGE


BODY

wght


Turns of the cochlea ju


Turns of the cochlea M


ED AVERAGE




I


II


ill


IV


Average


I


II


ill


IV


Average



days


gms.













1


5


8.6


8.3


7.8


7.8


8.1


7.7


8.1


7.4


7.6


7.7


7.8


3


8


8.6


8.5


8.2


7.8


8.3


8.3


8.4


8.J


7.5


8.1


8.2


6


11


8.5


8.6


8.3


8.0


8.3


8.0


8.0


8.1


7.9


8.0


8.1


c


10


8.7


8.5


8.2


8.7


8.5


76


7.9


8.4


8.2


8.0


8.1


12


13


7.6


7.7


7.5


7.9


7.7


5.8


6.5


6.8


7.4


6.6


6.9


15


13


7.5


7.5


7.7


7.9


7.6


6 1


6.6


6.8


7.0


6.6


6.9


20


29


7.0


7.3


7.6


7.8


7.4


6.0


6.4


6.9


7.3


6.6


6.8


Av. 11


14


8.0


8.0


7.9


8.0


8.0


7.0


7.3


7.5


7.6


7.3


7.5


25


36


7.3


7 2


7.2


7.1


7.2


6.0


6.3


6.3


6.5


6.3


6.5


50


59


7.0


75


7.3


7.3


7.3


6.0


6.2


6.3


6.7


6.3


6.6


100


112


6.7


7.0


7.1


7 1


7.0


5.8


6.0


6.0


6.0


5.9


6.2


150


183


6.6


6.8


7.0


7.3


6.9


6.0


6.0


6.2


6.1


6.0


6.2


257


137


6.6


6.9


7.0


7.7


7.0


5.9 16.0


6.2


6.4


6.1


6.3


366


181


7.6


7.4


7.3


7.2


7.4


5.9


6.0


6.1


6.0


6.0


6.4


546


255


6.5


6.5


6.5


7.1


6.6


5.8


6.0


6.1


6.4


6.1


62


Av. 213! 138


6.9


7.0


71


7.3


7.1


5.9


6.1


6.2


6.3


6.1


6.3


Ratios 1- 12 days


1:1. 0,|


1 :0.9|| 1 :0.9


1- 20 "


0.9


0.9 :0.9


1-546 "


0.8



O.S 0.8


20-546 "


0.9 |


0.9 :0.9


TABLE 69 Average volumes of the nuclei of the inner and outer hair cells (charts 33, 34 and 36)


AGE


BODY WEIGHT


VOLUME OF NUCLEUS HAIR CELLS

Inner Outer


WEIGHTED VOLUMES INNER AND OUTER HAIR CELLS


days


gms.


M'


M


M 3


1


5


278


239


248


3


8


299


278


289


6


11


299


268


278


9


10


322


268


278


12


13


239


151


172


15


13


230


151


172


20


29


212


151


165


25


36


195


131


144


50


59


204


131


151


100


112


180


108


125


150


183


172


113


125


257


137


180


119


131


366


181


212


113


137


546


255


151


119


125


Ratios 1- 12 days 1- 20 " 1-546 " 20-546 "


1 :0.9

0.8
0.5
0.7


0.6
0.6
0.5
0.8


0.7
0.7
0.5
0.8


100


GROWTH OF THE INNER EAR OF ALBINO RAT


101


The growth of the inner hair cell. The volume of the inner hair cell table 67 (chart 34) increases with age up to twenty

TABLE 70

Weighted volumes of the inner and outer hair cells according to the turns of the

cochlea


AGE


BODY WEIGHT


TURNS OF THE COCHLEA M*


I


II


ill


IV


days


gms.






1


5


795


715


587


427


3


8


940


1038


952


657


6


11


1129


1088


1177


905


9


10


1048


1415


1593


1574


12


13


1002


1361


1679


1664


15


13


1011


1288


1672


1701


20


29


1052


1352


1698


2017


25


36


1011


1346


1632


1775


50


59


978


1306


1640


1911


100


112


966


1367


'1569


1807


150


183


965


1237


1773


1917


257


137


991


1304


1601


1939


366


181


992


1320


1693


1957


546


255


940


1374


1681


1944


Ratios 1- 12 days


1 : 1.3 1


1.9


1 :2.9


1 :3 9


1- 20 "


1.3


1.9


2.9


4.7


1-546 "


1.2


1.9


2.9


4.6


20-546 "


0.9


1.0


1.0


1.0


TABLE 71 Condensed

Ratios of the weighted volumes of the inner -and outer hair cells according to the turns

of the cochlea




BATI08 BETWEEN TURNS


AGE


BODY WEIGHT


I-II


i-ni


I-IV


days


0ms.





1


5


1 :0.9


1 :0.7


1 :0.5


8


11


1.2


1.3


1.2


18


21


1.3


1.6


1.8


213


138


1.4


1.7


1.9


days; to nine days rapidly, then slowly. After twenty days it decreases slowly, as do the weighted volumes of the inner and outer hair cells, and with fluctuations, is nearly the same after


102


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


100 days. The three condensed age groups show that from 1 to 11 days it has increased 80 per cent, while from 11 to 213 days it has gained less than 2 per cent.

TABLE 72

Weighted diameters of the nuclei of the inner and outer hair cells according to the

turns of the cochlea


AGE


BODY WEIGHT


TURNS OF THE COCHLEA M


I


II


ill


IV


days


gms.






1


5


7.9


8.2


7.5


7.7


3


8


8.4


8.4


8.1


7.6


6


11


8.1


8.2


8.2


7.9


9


10


7.9


8.1


8.4


8.3


12


13


6.3


6.8


7.0


7.5


15


13


6.5


6.8


7.0


7.2


20


29


6.3


6.6


7.1


7.4


25


36


6.3


6.5


6.5


6.7


50


59


6.3


6.5


6.6


6.9


100


112


6.0


6.3


6.3


6.3


150


183


6.2


6.2


6.4


6.4


257


137


6.1


6.2


6.4


6.7


366


181


6.3


6.4


6.4


6.3


546


255


6.0


6.1


6.2


6.6


Ratios 1- 12 days


1 :0.8


1 :0.8


1 :0.9 1


1.0


1- 20 "


0.8


0.8


0.9


1.0


1-546 "


0.8


0.7


0.8


0.9


20-546 "


1.0


0.9


0.9


0.9


TABLE 73. Condensed

Ratios of the weighted diameters of the nuclei of the inner and outer hair cells according to the turns of the cochlea




RATIOS BETWEEN TURNS


AVERAGE AGE


AVERAGE BODY




WEIGHT







I-II


i-m


I-IV


days


gms.





1


5


1 :1.0


1 0.9


1 1.0


8


11


1.0


1.0


1.0


18


21


1.0


1.1


1.1


213


138


1.0


1.0


1.1


From nine days on the volume of the inner hair cell increases in passing from the base to the apex. During the earlier stages


GROWTH OF THE INNER EAR OF ALBINO RAT


103


there are some fluctuations (table 67, chart 35). In the con- densed table 74 the general relations are shown. The growth of the nuclei of the inner hair cells in diameter is given in table 68. As we see, the diameters increase from birth to nine days, then decrease slowly but steadily. In the three average age groups, however, the values decrease continuously with age. In table 69 are given the values for the volumes of the nuclei of the inner hair cell (chart 34).

TABLE 74 Condensed Ratios of the volume of the inner hair cells according to the turns of the cochlea




RATIOS BETWEEN TURNS


AVERAGE AGE


AVERAGE BODY




WEIGHT







I-II


i-in


I-IV


days


grams





1


5


1 0.8


1 0.7


1 0.5


11


14


1.1


1.2


1.2


213


138


1.1


1.3


1.5


TABLE 75 Condensed

Ratios of the diameters of the nuclei of the inner hair cells according to the turns of

the cochlea




RATIOS BETWEEN TDRN8


AVERAGE AGE


AVERAGE BODY




WEIGHT







I-II


I-II I


I-IV


days


grams





1


5


1 1.0


1 :0.9


1 0.9


11


14


1.0


1.0


1.0


213


138


1.0


1.0


1.1


The ratios of the diameters of the nuclei of the inner hair cells decrease at the earlier ages in each turn from the base to the apex. After nine days they are nearly the same in all the turns (tables 68 and 75), though their absolute values decrease in all the turns after nine days.

The growth of the outer hair cells. In general, the changes in the volume of the outer hair cells are like those in the inner hair cells. Therefore, the volume increases strikingly up to nine days of age, then gradually to twenty days. The main dif-


104


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


ference is that the volume in the outer hair cells does not diminish so much after twenty-five days, but holds nearly the same value (table 67, chart 36). In condensed age groups, therefore, we see a large increase in the size of the cells with age.

To determine the growth of the outer hair cells in each turn of the cochlea, table 67 is used (chart 37). From twenty days on the values increase from the basal to the apical turn. Before twenty days the relations are irregular or reversed. In table 76 this relation is clearly brought out.

Comparing the changes of the volume of the outer hair cells in three age groups (table 67), we find that the average volume increases throughout each turn with age, except in turn I, where


TABLE 76 Condensed Ratios of the volumes of the outer hair cells according to the turns of the cochlea




RATIOS BETWEEN TURNS


AVERAGE AGE


AVERAGE BODY




WEIGHT







I-II


i-in


I-IV


days


grams





1


5


1 1.0


1 0.8


1 0.6


11


14


1.3


1.6


1.5


213


138


1.5


1.9


2.2


that at eleven days is largest. In the inner hair cells, however, values at eleven days are largest in both turn I and II.

For the nuclei of the outer hair cells, the diameters are given in table 68). Here the d ! ameters tend to increase from one to nine days. At twelve days they decrease strikingly, and after that very slowly. In table 69 are given the values for the volumes of the nuclei of the outer hair cells.

In table 68 are given also the measurements for the nuclei of the outer hair cells according to the turn of the cochlea. At nine days and after, the diameters become larger in passing from base to apex, while in the earlier stages this relation is irregular or reversed. The decrease of the measurements in, each turn with age is clearly shown in the three age groups.


GROWTH OF THE INNER EAR OF ALBINO RAT


105


In table 77 are given the average ratios of turn I to the three other turns.

The comparison of the growth of the inner and outer hair cells. As already stated, the growth of the inner and outer hair .cells in volume proceeds in about the same way till they reach their full size at twenty days. After that we note a difference between them. While the outer hair cells maintain a nearly constant volume, the volume of the inner hair cells diminishes

TABLE 77 Condensed

Ratios of the diameters of the nuclei of the outer hair cells according to the turns of

the cochlea




RATIOS BETWEEN TURNS


AVERAGE AGE


AVERAGE BODY




WEIGHT







I-II


I-II I


I-IV


days


grams





1


5


1 1.1


1 1.0


1 1.0


11


14


1.0


1.1


1.1


213


138


1.0


1.1


1.1


TABLE 78 Condensed Comparison of the volumes of ike inner and the outer hair cells




AVERAGE VOLUMES HAIR CELLS



AVERAGE AGE


AVERAGE BODY



RATIOS OF INNER



WEIGHT




TO OUTER




Inner


Outer



days


grams


M


A



1


5


925


533


1 0.6


11


14


1665


1169


0.7


213


138


1693


1385


0.8


somewhat with age. When we consider the volume according to the three age groups, it increases in both groups throughout life (table 78). There are, however, large differences in the rate of increase. The inner hair cell increases its volume at 11 days by 80 per cent and between 11 and 213 days by less than 2 per cent. For the outer hair cells the increase by 11 days is 120 per cent and from 11 to 213 days, 19 per cent. At the same time the inner are always larger than the outer hair cells, as the ratios in table 78 show.


106


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


The diameters of the nuclei in both the inner and outer hair cells diminish in value after nine days of age. This decrease is larger in the outer than in the inner cells. In table 79 are given the values for the diameters of the nuclei in both inner and outer hah* cells. In the last column are the ratios between them.

Thus, while the volumes of the outer hair cells, as compared with the inner hair cells, become relatively larger with age (table 78), the diameters of their nuclei become relatively smaller (table 79).

TABLE 79 Condensed Comparison of the diameters of the nuclei of the inner and outer hair cells




AVERAGE DIAMETERS OF THE





AVERAGE


NUCLEI OF THE HAIR CELLS


RATIOS OF THE AVERAGE DIAMETERS OF THE NUCLEI OP


AVERAGE AGE


BODY






WEIGHT


Inner


Outer


CELLS


days


grams


M


M




1


5


8.1


7.7


1 1.0



11


14


8.0


7.3


0.9



213


138


7.1


6.1


0.9



Comparison of the growth of the inner and outer hair cells according to sex. A careful and elaborate comparison has been made to determine whether there are differences in the growth of the hair cells according to sex.

In table 80 are given the average values for the volumes of the cell bodies and their respective nuclei. No significant differ- ences according to sex were found.

Comparison of the growth of the inner and outer hair cells according to side. The same treatment of the data was followed as in the determination for the influence of sex. In table 81 are given the average values for the volumes of the inner and outer hair cells and their respective nuclei. Again no significant differences according to side were found.

On the nucleus-plasma ratios of the inner and outer hair cells. For the inner and outer hair cells here measured the weighted volumes of the cell bodies and of their nuclei are entered in the condensed table 82, and the ratios of the volume of the nucleus


GROWTH OF THE INNER EAR OF ALBINO RAT


107


to that of the cytoplasm (=cell volume less nucleus volume) are given in the last column. This ratio increases with age, as table 82 shows. While the ratio is 1.5 in the youngest and smallest group, it is 9.9 in the largest. This means that as a group these cells are continually growing in volume. This result may be analysed for the two groups of cells involved.

TABLE 80

Average volumes of inner and outer hair cells and of their respective nuclei

in n 3 according to sex






INNER HAIR CELLS


OUTER HAIH CELLS


WEIGHTED AVERAGE


Att


BODY


NO. OF


BEX


Average volume


Average volume


VOLUME




BATS










Cell


Nucleus


Cell


Nucleus


CELLS


NUCLEI


da j/5


grams










3


7


1


0*


1213


310


815


268


915


278



8


1


9


1319


310


888


322


996


319


6


11


2


tf


1426


289


955


278


1073


281



10


2


9


1372


310


979


268


1077


278


9


10


2


cT


1701


310


1351


258


1439


271



9


2


9


1895


345


1203


278


1376


295


12


14


2


c? 1


1830


258


1344


157


1466


182



12


2


9


1886


221


1221


151


1387


168


100


146


1


cT


1687


180


1342


113


1428


129



103


1


9


1779


212


1319


108


1434


184


150


189


1


rf 1


1679


165


1382


119


1456


131



154


1


9


1639


212


1611


119


1618


142


365


205


1


tf


1739


258


1389


119


1477


154



170


1


9


1659


221


1486


113


1529


140


Volume greater in male 3


2


3


4


5


3


Volume greater in female 4


4


4


2


2


4


Equal


1



1



.


The nucleus-plasma ratio of the inner and outer hair cells considered separately. This is shown for the inner hair cells in table 83. The ratios are also progressive, but somewhat larger for the earlier age groups and smaller for the oldest, than in the previous instance.

The ratios for the outer hair cells are also progressive, and the range is greater than for the inner hair cells as table 84 shows. Here the ratio is 1.2 for the youngest group and 10.6 for the


108


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


oldest. This indicates that at one day and eleven days the relative volume is less in the outer than in the inner hair cells, but at the later age the outer hairs cells grow more.


TABLE 81


Volumes of the inner and outer hair cells and of their respective nuclei according

to side in ft 3


AGE


BODY WEIGHT


NO. OF

BATS


SIDE


INNER HAIR CELLS


OXJTER HAIR CELLS


WEIGHTED AVERAGE VOLUME


Average volume


Average volume


Cell


Nucleus


Cell


Nucleus


CELLS


NUCLEI


1


5


2


R.


895


299


555


248


640


261





L.


955


268


511


230


622


239


3


7


1


R.


1213


310


815


268


915


278





L.


1395


299


920


299


1039


299


6


11


2


R.


1381


322


1010


278


1103


289





L.


1416


289


923


258


1046


268


9


9


2


R.


1782


310


1177


268


1328


278





L.


1815


333


1378


268


1487


284


12


12


1


R.


1887


212


1310


151


1454


166





L.


1885


221


1132


151


1320


168


15


13


1


R.


1895


230


1522


144


1615


165





L.


1848


239


1419


151


1526


172


20


29


2


R.


1914


212


1365


144


1502


161





L.


1862


221


1472


165


1570


179


25


36


2


R.


1758


204


1307


131


1420


149





L.


1792


195


1351


131


1461


147


50


59


2


R.


1741


204


1443


125


1518


145





L.


1687


204


1305


137


1401


154


100


102


2


R.


1675


187


1355


113


1440


131



123


2


L.


1658


172


1339


113


1419


128


150


189


1


R.


1565


172


1420


113


1456


128





L.


1679


165


1382


119


1456


131


257


137


2


R.


1685


187


1377


125


1454


140





L.


1607


180


1416


119


1464


134


367


175


2


R.


1634


195


1436


113


1486


134


365


188


2


L.


1848


230


1374


113


1493


142


546


255


2


R.


1831


157


1474


119


1563


128





L.


1559


151


1353


119


1405


127


Volume greater on right side 7


8


9


3


7


6


Volumfe greater on left side 7


5


5


5


6


8


Equal


1



6


1




GROWTH OF THE INNER EAR OF ALBINO RAT


109


This seems to be important and to illustrate the fact that in the papilla spiralis the growth of the elements lying nearer the axis occurs earlier than that of the elements nearer the periphery.

TABLE 82 Condensed Nucleus-plasma ratios of the inner and outer hair cells M*


AVERAGE AGE


AVERAGE BODY WEIGHT


AVERAGE VOLUME OF INNER AND OUTER HAIR CELLS


VOLUME OK CYTOPLASM


NUCLEUS- FLA8MA RATIOS


Cell


Nucleus


days

1

11

213


grams 5 14 138


631 1293 1462


248 226 134


383 1067 1328


1 : 1.5

4.7-
9.9


TABLE 83 Condensed Nucleus-plasma ratios of the inner hair cells /**


AVERAGE AGE


AVERAGE BODY WEIGHT


AVERAGE VOLUME OF 1XXER HAIR CELLS


VOLUME

or

CYTOPLASM


NUCLEUS- PLASMA RATIOS


Cell


Nucleus


days 1 11 213


0ms.

5

14 138


925 1665 1693


278 268 187


647

1397 1506


1 2.3 5.2 8.1


TABLE 84 Condensed Nude us- plasma ratios of the outer hair cells


AVERAGE AGE


AVERAGE BODY WEIGHT


AVERAGE VOLUME OF OUTER HAIR CELLS


VOLUME or

CYTOPLASM


NUCLEUS- PLASMA RATIOS


Cell


Nucleus


days 1 11 213


grams 5 14 138


533 1169 1385


239 204 119


294

965 1266


1 1.2

4.7 10.6


17. Deiters' cells. The Deiters' cells are most delicate ele- ments. In the literature, so far as I know, there are no exact observations touching the growth of these cells in the papilla spiralis, except a few data for their length. They have an


110 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON

irregular form and consist of three parts, the phalangeal process, cell body, and foot. The phalangeal process is thin, somewhat crooked in the adult though it runs straight at an earlier stage. As the boundary between this process and the cell body, we take a line running through the supporting cup ('Stutzkelch' of Held) parallel to the plane of the basilar membrane (fig. 10). The cell body in its upper part is wide, including here a round nucleus. It then becomes thin and passes over to the foot. Thus it is almost impossible to get the true volume of the cells. Therefore, we have determined the volume of the cell body only, excluding that of the phalangeal process.

We think of the cell body as a cylinder having an average diameter, which is calculated from four diameters measured at four levels. The first level is just below the upper boundary of the cell body, the second in the widest part, the third below at about the middle of the cell body, and the last is at the narrowest part near the foot. .

The height of the cylinder is the length of the cell body within the limits just noted. Thus the volume obtained approximates the value for the natural size of the cell body without the process.

In table 85 (chart 38) are given the values for the volumes of the Deiters' cells thus computed and the diameters and volumes of the nuclei according to age. As there are in the radial section three rows of cells, the values given are, of course, the average of these. At the bottom of the last column appear the ratios at 1 to 12, 1 to 20, 1 to 546, and 12 to 546 days. As we see, the volume of the cell body increases throughout life, slowly during the first nine days, but from twelve to twenty days very rapidly, and then less rapidly to old age.

While the ratio from one to twelve days is 1:5.4, that from 1 to 546 days is 1:29.1, or more than five times as large.

When we consider the volumes of the cells in each turn of the cochlea, we see that it is smallest in turn I and largest in turn IV, though there are some exceptions before nine days of age. Table 86 shows these relations.

The diameters of the nuclei of the cells grow, after some fluctuations in the values at earlier stages, very slowly to old


GROWTH OF THE INNER EAR OF ALBINO RAT 111

age, as indicated in table 85 and chart 38. The ratios at the bottom of the corresponding column show these relations. The values for the volumes of the nuclei of the cells are given in the last column. Here, also, the diameters in the upper turns tend to be larger than in the basal turn. In table 87 are given the ratios of the diameters of turn I to the three other turns. We see in all the turns about the same ratios, 1:1.0.

In the literature we find but two observations on the diameters of the nuclei of the Dieters' cells. Kolmer ('07) reports hi the pig 5 [i, and von Ebner ( '02) gives in man 7 (x for the diameter of the round nucleus of the cells.

In the rat, therefore, the diameter is larger than in these two forms, but no significance can be attached to this difference until correction has been made for the several techniques em- ployed. This I am unable at present to do.

On the nucleus-plasma ratio in Deiters 1 cells. In the condensed table 88 are given the volumes of the cell bodies and of their nuclei together with the respective nucleus-plasma ratios. This shows that the ratio is progressive with age. While the ratio is at birth only 0.05, that in the oldest group is 28.3. The absolute increase is not great at earlier stages, but by eighteen days it is marked

The rapid change in the ratio is very interesting. Before eight days of age the cells are still immature. Some time after eight days they develop rapidly, seeming to play some important part in the special functions of the cochlea.

On the length of Deiters' cells. To measure the length of Deiters' cells we divide them into two parts, the upper and the lower, by the boundary line between the cell body and the pha- langeal process. The sum of these two lengths makes the total length of the cells.

In table 89 are given the values for the total length and for each part separately (chart 39). As in the volume of the cells, we see an astonishing change in the development of the length. The length of the cells increases through life, at earlier stages a little, but at twelve days it becomes nearly twice as long as at nine days. The ratios at the bottom of the last column show the course of growth.


TABLE 85

The volume of Deiters' cells and the mean diameters and volumes of their respective

nuclei (chart 38)




VOLUME OF THE DEITERS* CELLS


1

NUCLEI


VOLUMES



BODY


fit


Diameters



AGE


WEIGHT











Average





I


II


III


IV


Average


I


II


III


IV


diam-


Average








volume






eters


volumes













M


M


days


grams













1


5


278


232


237


256


251


7.6


7.5


7.5


8.1


7.7


239


3


8


290


309


349


352


325


7.0


7.0


6.9


7.0


7.0


180


6


11


425


395


495


364


420


7.0


6.5


6.7


6.6


6.7


165


9


10


635


461


554 423


518


6.9


7.0


7.1


7.1


7.0


180


12


13


1122


1369 1395


1569


1364


6.5


7.0


6.9


7.1


6.9


180


15


13


1466


2187 2659


3127


2359


7.0


7.2


7.2


7.3


7.2


195


20


29


3576


427115740


6171


4939


7.6


7.8


7.9


7.9


7.8


248


25 50


36 59


4088 4467 5470 4839 5970 6258


5757 6816


4695 5971


7.3 7.3


7.2 7.5


7.3

7.5


7.4 7.4


7.3 7.4


212 212


100


112


5011


6083


7137 6607


6210


6.9


7.6


7.5


7.4


7.3


212


150


183


5755 6291 7657


6750


6613


7.5


7.6


7.5


7.1


7.4


212


257


137


5776 6540 8841


8544


7425


7.4


7.8


7.9


8.0


7.8


248


366


181


6163


6908


7701


7895


7167


7.4


7.7


7.9


7.9


7.7


248


546


255


6092 6919 8028


8152


7298


7.4


7.9


8.0


7.7


7.7


248


Ratios 1 12 days


1 5.4






1 0.9



1 20 "


19.7






1.0



1546 "


29.1






1.0



12546 "


5.4

!






1.1



TABLE 86 Condensed Ratios of volumes of the Deiter's cells according to turns of the cochlea




RATIOS BETWEEN TURNS


AVERAGE AGE


AVERAGE BODY




WEIGHT







I-II


i-m


I-IV


days


grams





1


5


1 :0.8


1 :0.9


1 :0.9


8


11


1.0


1.1


1.1


18


21


1.3


1.7


1.8


213


138


1.1


1.4


1.3


TABLE 87 Condensed Ratios of the diameters of the nuclei of Deilers' cells according to turns of the cochlea




RATIOS BETWEEN TURNS


AVERAGE AGE


AVERAGE BODY




WEIGHT






I-II


I-III


I-IV


days


grams





1


5


1 1.0


1 1.0


1 : 1.1


8


11


1.0


1.0


1.0


18


21


1.0


1.0


1.0


213


138


1.0


1.1


1.0


112


GROWTH OF THE INNER EAR OF ALBINO RAT


113


90OO


8OOO


7OOO


6000


5000


4000


3OOO


2OOO


1OOO




AGE


o


25


50


50 1OO 2OO 300 4OO 5OO


Chart 38 Showing the volume of Deiters' cells and their nuclei, on the average and according to the turns of the cochlea, table 85. Average volume of Deiters' cells.

._. Volume of the cells in about the middle of the basal turn.

Volume of the cells in about the beginning of the middle turn.

Volume of the cells in about the middle of the middle turn.

-..-..-.. Volume of the cells in about the beginning of the apical turn. -...-.. Average volume of nuclei of Deiters' cells, X 10.


114


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


Comparing the length of the cells according to the turn of the cochlea, we find that after twelve days the length increases from the base to the apex, in turn III very rapidly, in turn IV gradually (table 90). At earlier stages the relations are irregular.


TABLE 88 Condensed Nucleus-plasma ratios of the Deiters' cells




AVERAGE VOLUMES







VOLUME OF


NUCLEUS-


AVERAGE AGE


AVERAGE BODY




CYTOPLASM


PLASMA RATIOS



WEIGHT


Cell


Nucleus


.M





M


M




days


grams






1


5


251


239


12


1 : 0.05


8


11


657


172


485


2.8


18


21


3649


221


3428


15.5


213


138


6483


221


6262


28.3


TABLE 89

Length of cell body and of processus phalangeus of Deiters' cells p (chart 39)




LENGTH OF THE CELL BODY


LENGTH OF THE PROCESSUS






PHALANGEUS







TOTAL



BODY




LENGTH


AGE


WEIGHT


Turns of cochlea


Turns of cochlea


OF THE






CELLS




I


II


III


IV


Average


I


II


ill


IV


Average



days


gms













1


5


8


8


8


9


8


20


19


20


15


19


27


3


8


8


9


9


10


9


16


17


18


18


17


26


6


11


9


9


11


10


10


19


22


23


22


22


32


9


10


18


12


13


11


14


18


21


26


24


22


36


12


13


31


35


40


43


37


18


22


29


25


24


61


15


13


34


37


40


43


39


21


25


32


31


27


66


20


29


39


41


49


49


45


19


23


30


34


27


72


25


36


42


43


51


51


47


17


21


30


32


25


72


50


59


41


45


53


53


48


16


22


30


34


26


74


100


112


43


45


54


53


49


17


25


29


31


26


75


150


183


45


46


53


52


49


17


22


32


34


26


75


257


137


43


46


56


58


51


18


24


28


31


25


76


366


181


43


48


55


55


50


17


23


29


32


25


75


546


255


46


49


56


56


52


16


23


30


33


26


78


Ratios 1 12 days



1 :4.6






1 :1.3


1 :2.3


1 20 "



5.6






1.4


2.7


1546 "



6.5






1.4


2.9


12546 '"



1.4






1.1


1.3


GROWTH OF THE INNER EAR OF ALBINO RAT


115


When we consider the length of the cell body, it is remarkable that the increase takes place so rapidly. While at 1 day it measures only 8 (x and at nine days only 14 ji, it increases very suddenly at twelve days of age, and after that slowly but con- tinuously (table 89).

TABLE 90 Total length of Deiters' cells according to turns of the cochlea (chart 39)


AGB


BOOT WEIGHT


TURNS OF THE COCHLEA


I


II


III


IV


days


grams






1


5


28


27


28


24


3


8


24


26


27


28


6


11


28


31


34


32


9


10


36


33


39


35


12


13


49


57


69


68


15


13


55


62


72


74


20


29


58


64


79


S3


25


36


59


64


81


83


50


59


57


67


83


87


100


112


60


70


83


84


150


183 '


62


68


85


86 -


257


137


61


70


84


89


366


181


60


71


84


87


546


255


62


72


86


89


80 M 60

40

20 n

















































































^


<















="




>


"^






/

































/
































































































-











-





~




~






















/

































,'

































>

P

































-



































  • -.

































'*



































,/

































"'



























ft


G


E


DA


  • /c






























Tb


25 50 50 10O 200 30O 400

Chart 39 The length of Deiters' cells, tables 89 and 90.


500


Total length of the cells. Length of the cell bodies. Length of processus phalangeus.


116


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


In the ratios at the bottom of table 89 this is shown very evidently and in each turn this relation is to be seen.

For the length of the phalangeal process the story is quite different. It increases from birth to twelve days a little; at fifteen days it reaches full size, and then holds its value (table 89) . After three days the length is smallest in turn I and largest in turn IV. This relation lasts to old age.

Comparing the growth of the length of the cell body and phalangeal process, there is a large difference between them. While the length in the phalangeal process is at birth over twice that of the cell body, at 546 days it is only half that of the cell

TABLE 91

Total length of Deiters' cells in fj, (Retzius)


AGE



RABBIT


CAT



Basal


Middle


Apical


Average


Basal


Middle


Apical


Average



turn









New-born


48


70


60


59


45


65


48


53


2


45


66


54


55






1


3








45


60





7


80


90


75


82


49


69


63


60


10


98


100


114


104








11








75


90


45


70


14


84


105


112


100








30








54


75


70


66


body. Thus the increase of the total length of Deiters' cells is due chiefly to the increase in the length of the cell body.

Retzius ('84) gives the length of Deiters' cells in the rabbit and cat as in table 91.

Table 91 shows that in both the rabbit and the cat the length at all ages is greater, and especially at the earlier stage is twice as great, as in the rat. In the rabbit there is a rapid increase in length between seven and ten days. For the cat the values are smaller, nearer those of the rat, and show less change between birth and thirty days.

18. Summary and discussion. Using the foregoing data on the form and measurements of the elements of the cochlear duct, I desire here to summarize the results and to discuss the consequent changes in the form of the organ of Corti (table 92).


GROWTH OF THE INNER EAR OF ALBINO RAT 117

We have already noted that at birth the greater epithelial ridge constitutes the main part of the tympanic wall, and the lesser epithelial ridge, from which arises later the most important organ, is represented by a small and undeveloped prominence. With age this greater ridge disappears gradually and is trans- formed into a furrow lined with low epithelial cells, the sulcus spiralis internus (Waldeyer). These changes appear first at the base and then pass gradually to the upper turns. In the lesser ridge also there are important developmental changes. At first the hair cells and pillar cells grow, and just before the special function appears, striking changes are seen in Deiters' and Hensen's cells. These increase, especially in their length, very rapidly.

Thus the papilla spiralis, which hitherto had its highest point at the summit of the arch of Corti, shows a remarkable change of form, as the outer part of the papilla increases its height, so that finally Hensen's cells mark the highest point in the papilla. The surface then ceases to be parallel to the basilar membrane, and slopes inward, making with the basilar membrane an acute angle opening outward. At the same time the papilla spiralis appears to be shifted inward i.e., towards the axis.

Kolliker has described how the cells, from which the pillars or rods of Corti arise, at first stand nearly parallel, but later separate at their base. He thought that this "von einem Langen- wachstum (?) der Zellen selbst oder ihrer Grundlage, der Mem- brana basilaris, abhiingen kann. "

Hensen ('63) first studied this interesting problem in the ox and found it to depend on a peculiar process. He regarded the inward migration as taking place chiefly in the inner pillar cell. The outer pillar cell in the upper turn moves somewhat outward ; in the base, however, inward. Moreover, the outer pillar cell increases its length during the development of the papilla much more than the inner does. Thus the summit of the arch of Corti and therefore the papilla spiralis shifts inward on the basilar membrane.


118


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON




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GROWTH OF THE INNER EAR OF ALBINO RAT


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120

Bottcher ( '69. 72) disagreed with Hensen, though he has con- firmed, as did Middendorp ('67), the striking inward spreading of the base of the inner pillar cell.

Gottstein] ( 72) held that the inner pillar cell does not move inward, but that the increase in the length of the labium tym- panicum may explain the peculiar approach of the habenula perforata to the arch of Corti.

Retzius ('84) agreed in general with Hensen 's assertion that in the course of development the surface of the sense organ comes to lie under the basal surface of the membrana tectoria. He thought that this change of position is brought about "weni- ger in dem Verhalten der Pfeilerzellen, sondern vor allem in dem starken Wachstum der Deitersschen Zellen und der von aussen andriickenden Hensenschen Stiitzzellen, ' and that, further, "vielleicht die Membrana tectoria selbst durch eigenes Wachstum und durch Vergrosserung des Limbus mit seinem Vorspriingen" contributes to this.

Held ('09) agrees with Hensen on the whole.

Prentiss ('13, p. 450) denies the wandering of the spiral organ as follows: There is no necessity for, and my preparations afford no proof of, an inward shifting of the spiral organ and a consequent displacement of the membrana tectoria "

Hardesty ('15, pp. 60 and 61) discussed the relative position of the spiral organ with reference to the basal surface of the tectorial membrane and says " the developed spiral organ acquires its position well under the basal surface of the tectorial membrane almost entirely by being carried axisward during the completion of the membrane." "In the apical turn, where these changes are greatest, the hair cells of the organ may be carried axisward a distance nearly half the width of the membrane. The upgrowth of the outer supporting cells also forces axisward the apical ends of the elements of the spiral organ and in this way con- tributes a small part to the shift in the relative position of the hair cells. A slight increase in width of the vestibular lip of the spiral limbus may contribute a still smaller part by extending the membrane outward."


GROWTH OF THE INNER EAR OF ALBINO RAT 121

I obtained from the measurements given in the tables the following results concerning the position of the papilla spiralis under the basal surface of the tectorial membrane.

As already stated, since the habenula perforata may be con- sidered after birth as a punctum fixum (Hensen), it is found that the inner pillar cell shifts inward at its inner basal corner during the earlier stage of life. At six days of age it almost always reaches the habenula perforata in the basal turn, though not yet in the apical. At nine days there is no distance between the- habenula perforata and the inner corner of the inner pillar cell.

Gottstein's assumption (no measurements) that the labium tympanicum grows outward and approaches to the arch of Corti is not applicable to the rat, as shown by my tables.

The outer pillar cell also moves outward in all the turns through life, but only slightly after nine days. This result does not agree with that of Hensen ('63), who found in the ox the outer pillar cell to move inward a little at the base, not at all in the middle turn and outward at the apex. Bottcher 's outward movement of the outer pillar cell at the hamulus in the cat is 90 y. and much larger than in the rat.

Contrary to Hensen, Retzius ('84) also finds in the rabbit an outward movement of the base of the outer pillar cell throughout all the turns. On the other hand, during the earlier stages of development, the top of the arch of Corti moves outward from the labium vestibulare through the outward pressure of the greater epithelial ridge. At this stage the main part of the membrana tectoria does not yet reach to the sense cells, though the part produced from the lesser epithelial ridge spans the spiral organ and connects with the outer part of the papilla.

After nine days of age the condition of the organ is quite different. The most remarkable anatomical changes from the earlier condition are the rapid increase in the length of the outer pillar cells, in the height of the pillar cells above the basilar membrane, in the height of the papilla spiralis at the third series of the outer hair cells, in the height of Deiters' cells, and in the height of Hensen 's supporting cells. Also the tunnel of Corti appears.


122 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON

The greater epithelial ridge has already disappeared in large part and been replaced by a furrow. Pressure displacement of tissue in the direction of the least resistance is common in organogenesis. Thus the inner pillar cell is subject to pressure by the rapid growth of the outward lying and greater part of the papilla spiralis and moves in the direction of the least resis- tance, therefore inward; the head most and the base not at all. As shown in table 44, the rapid decrease in the radial distance between the labium vestibulare and the head of the inner pillar cell is very evident. The arch of Corti changes its form, now inclining inward, instead of outward as heretofore. The lamina reticularis runs not parallel to the basilar membrane, but ascends outward. The tunnel of Corti also changes more or less its form. Nuel 's space now appears possibly as a result of this displacement of the papilla spiralis. Thus we see a change in the position of the sense organ with reference to the membrana tectoria.

With the inward shifting of the papilla, the hair cells come under the basal surface of the membrana tectoria. It is probable that the increase of the relative length of the membrane also takes part in this, since the increase in the breadth of the inner zone of the membrana tectoria from one to twelve days is as 1:3.4 (table 4), while the increase in the breadth of the basilar membrane is as 1:0.5 during the same interval (table 7).

Prentiss' ('13) statement that an inward shifting of the papilla spiralis and a consequent displacement of the membrana tectoria does not take place (in the pig) is not applicable to the rat.

In the rat the labium vestibulare and the inner edge of the head of the inner pillar cell are also two definite points in the same sense, and using them we see an inward shifting of the organ of Corti. I imagine that his observation may have misled him, since the tectorial membrane arises in his preparations from both greater and lesser epithelial ridges, and from the earlier stages covers with its outer part the papilla spiralis. Thus the shifting of the organ inward does not necessitate a change in the position of the papilla with reference to the mem- brane. In his study of the tectorial membrane in the same animal (pig) , Hardesty ( ' 13) describes a large displacement of the papilla spiralis inward.


GROWTH OF THE INNER EAR OF ALBINO RAT 123

According to him, the shifting of the organ consists of, 1, the moving axisward of the organ itself, and this constitutes the main shift; 2, the upgrowth of the outer supporting cells, and this contributes a small part to the shift, and, 3, a slight increase of the vestibular lip of the spiral limbus which may contribute a still smaller part. The relation in the rat, however, is different. The moving inward of the papilla itself is not seen in the rat. In the earlier stages the inner basal corner of the inner pillar cell alone shifts inward and reaches the habenula perforata. On the other hand, the outer pillar cell moves outward and the head of the inner pillar cell also, at earlier stages, towards the cells of Hensen. Therefore, during the earlier stages the arch of Corti moves rather outward, owing to the pressure of the growth of the greater epithelial ridge. Since the habenula perforata is to be regarded as a fixed point, the inward displace- ment of the head of the arch of Corti and of the papilla spiralis is not due to the active shifting inward of the organ itself, as Hardesty ('15) thinks, but to the disappearance of the greater ridge and the passive pressure exerted by the upgrowth of the outer pillar cells and Deiters' and Hensen 's cells. The vestibular lip of the spiral lamina and the tectorial membrane itself both increase in their length a little, and these increases play some part in the change of the position of the papilla spiralis with reference to the basal surface of the tectorial membrane.

The membrana basilaris is not concerned with the moving inward of the organ. It increases its length with age in all the turns, but we do not find the change in the position of the feet of the pillar cells on the membrane in such a sense that the feet move inward on it.

Thus the shifting of the papilla spiralis inward in the rat during the development takes place rather in the manner de- scribed by Retzius.

Hardesty ('15) states that in the apical turn of the cochlea the organ may be moved axisward a distance equal to about half the maximum width of the greater epithelial ridge, the maximum width of the ridge representing approximately the width of the outspanning zone of the membrane produced upon it.


124


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


No other author reports such a high degree of the inward shifting of the organ. I have not studied the pig, but in the rat I get the average distance between the labium vestibulare and the inner edge of the head of the inner pillar cell as follows (table 93).

TABLE 93

Average distance between the labium vestibulare and the inner edge of the inner pillar cell in n (albino rat)


AGE


BODY WEIGHT


TURNS OF COCHLEA


I


II


III


IV


Average


days


grams







(1) 5 (2) 154 Difference betw 1 and 2


9 102 een age groups


94

63 31


124 100 24


1,54 134 20


165

148 17


23


Therefore, in the rat the organ moves inward on the average of 23 [A; that is, in the ratio of 1:0.16 of the maximum distance between these two points. It may be noted that the difference in this table is not the same in the several turns, but diminishes from base to apex a relation which is the reverse of that reported by Hardesty ('15) in the pig. I have no explanation for these differences except their possible dependence on the different animals used.

C. On the growth of the largest nerve cells in the ganglion spirale.

Observations. For the present studies the fourteen age groups used in the previous observations on the growth of the tympanic wall of the cochlear duct were employed. In order to see the relation between the growth of the papilla spiralis and the cells of the ganglion spirale, both studies were made on the same sections. In addition, however, I made cross-sections of the cochlea (i.e., at right angles to the axis) in several age groups to follow the growth and the changes in the form of the nerve cells as they appear in this plane. The data for the animals thus used are given in table 94.


GROWTH OF THE INNER EAR OF ALBINO RAT


125


For the measurement of the nerve cells a Zeiss system was used with a micrometer eyepiece, having each division equal to 2jx. Since we have in the radial vertical section of the cochlea of the rat at least four turns, there are four cell groups available in each section (fig. 3). The ten largest cells in each ganglion were measured, and thus a total of forty cells in a section were taken for the measurement of the nucleus and the cell.

We used, as stated, four cochleas in each age group, so that 160 cells were measured for each age. Also in the cross-sections the four nearly corresponding turns were used for the measure- ments, selecting the ten largest cells in each turn.

TABLE 04 Data on rals used for cross-sections of the cochlea ganglion spirale


AGE


BOOT WEIGHT


BODY LENGTH


BEX


8IDE


HEARING


days


grams






15


20


84


(?


L.


Prompt response


20


27


93


d"


L.



25


39


114


P


L.



100


95


152


<?


R.



150


169


192


9


L.



371


220


206


c?


L.



In the measurement of the cell bodies the two maximum diameters at right angles to each other were determined, and also the two corresponding diameters for the nuclei.

Here it is to be noted that the expressions turn I, II, III, and IV are used in the same sense as in the earlier chapters.

In table 95 (chart 40) are given the values for the average diameters of the cell bodies and their nuclei in the ganglion spirale in the radial vertical section according to fourteen age groups. Under 'cell body, diameter,' the first column gives the long, the second the short, and the third the computed diameter; i.e., the square root of their products. These last values ap- proximate the mean diameters of the nerve cells. At the foot of the third column are given the ratios from 1 to 20, 1 to 546, and 20 to 546 days. The values for the diameters of the nurlei are similarly given and also the ratios.


126


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


As the tables and charts show, the diameters of the cell bodies and also of their nuclei are largest at twenty days of age. After that age they diminish, gradually. While the ratio for one to twenty days is 1:1.7 in the cell bodies and 1:1.3 in the nuclei, that for 1 to 546 days is 1:1.6 and 1:1.2, respectively.

TABLE 95

Diameters of the cell bodies and their nuclei in the ganglion spirale (radial-vertica I

section) (chart 40)





Diameters in M





Cell body


Nucleus


AGE


BOOT


BODY





WEIGHT


LENGTH











Long


Short


Computed


Long


Short


Computed


days


grams


mm.








1


5


48


11.0


10.0


10.5


8.2


7.6


7.9


3


8


56


12.0


11.1


11.5


8.2


7.8


8.0


6


11


63


13.6


12.3


12.9


8.8


8.1


8.4


9


10


58


14.3


12.8


13.6


8.9


8.2


8.5


12


13


70


14.6


13.1


13.8


8.7


8.2


8.5


15


13


75


15.7


14.1


14.9


9.1


8.4


8.7


20


29


95


19.0


17.3


18.1


10.3


10.0


10.2


25


36


104


18.5


16.9


17.7


10.2


9.9


10.1


50


59


125


18.5


16.6


17.5


10.3


9.7


10.0


100


112


159


18.1


15.7


16.9


9.8


9.2


9.5


150


183


190


18.2


15.3


16.7


9.6


8.8


9.2


257


137


175


18.5


15.3


16.8


9.9


9.4


9.6


366


181


191


18.6


15.3


16.9


9.8


9.0


9.4


546


255


213


18.6


15.3


16.9


9.7


9.0


9.4


Ratios







120 days



1:1.7




1:1.3


1546 "



1.6




1.2


20546 "



0.9




0.9


In table 96 (chart 41) are a series of computed diameters of the cell bodies and of their nuclei according to the turns of the cochlea. At the bottom of each column are given the ratios from 1 to 20, 1 to 546, and 20 to 546 days. Determining the ratios for each column, it appears that in general the diameters of the cell bodies and their nuclei are largest at twenty days throughout all the turns. This increase is very considerable from fifteen to twenty days. Then they decrease very slowly till 546 days.


GROWTH OF THE INNER EAR OF ALBINO RAT


127


Table 97 enables us to compare the ratios in the diameters of the cell bodies and their nuclei in turns I, II, III, and IV in the condensed age groups. In both the cell bodies and their nuclei the ratios become slightly larger in passing from the basal toward the apical turn, except in the one day group, which it reversed.

On the comparison of the diameters of the nerve cell bodies and their nuclei in the ganglion spirale according to sex. For this comparison seven age groups were used. In each age group we have sometimes one, sometimes two cochleas of the same sex.


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Chart 40 Showing the computed diameter of the largest cell bodies and their nuclei from the ganglion spirale, table 95.

Diameters of the cell bodies.

Diameters of the nuclei.

In the latter case the average value is recorded. In table 98 are given the values for these diameters, and it is plain that there is no significant difference in these values according to sex. On the comparison of the diameters of the nerve cell bodies and their nuclei in the ganglion spirale according to side. For this purpose fourteen age groups were employed. In most cases two cochleas from the same side were used in each age group. In these cases the average value is recorded. Table 99 shows the values for the diameters of the cell bodies and their nuclei accord- ing to side, but reveals no evident difference in this character.


128


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


On the morphological changes in the ganglion cells during growth. As my sections could not be stained with thionine, my observations on the Nissl bodies are incomplete, yet the slides stained with Heidenhain's iron haematoxylin and van Gieson's stain, as well as by haematoxylin and eosin, were helpful here.


TABLE 96


Computed diameters of the cell bodies and their nuclei in the ganglion spirale according to the turns of the cochlea (chart 41 )


AGE

days


BODY WEIGHT

gms


TURNS OF THE COCHLEA


Computed diameters M


I


II


in


IV


Cell body


Nucleus


Cell body


Nucleus


Cell body


Nucleus


Cell body


Nucleus


1


5


11.0


8.0


10.8


8.2


10.4


8.0


9.6


7.4


3


8


11.5


7.9


11.5


7.9


11.7


8.0


11.3


8.1


6


11


12.9


8.4


12.6


8.2


13.0


8.5


13.3


8.6


9


10


13.4


8.4


13.4


8.5


13.6


8.6


13.7


8.6


12


13


13.6


8.1


13.5


8.1


13.8


8.6


14.7


9.0


15


13


14.8


8.6


15.0


8.6


14.6


8.6


15.0


9.2


20


29


17.6


10.0


17.6


9.9


18.1


10.2


19.0


10.4


25


36


16.9


9.9


17.6


10.0


17.6


10.1


18.4


10.3


50


59


17.2


9.7


17.2


9.7


17.6


10.0


17.9


10.1


100


112


16.9


9.6


16.9


9.4


16.3


9.3


16.9


9.6


150


183


16.9


9.3


16.3


9.0


16.6


9.1


17.0


9.1


257


137


16.7


9.6


16.7


9.4


16.9


9.7


17.0


9.7


366


181


16.7


9.3


16.4


9.2


16.7


9.1


17.7


9.7


546 255 Ratios 1 20 day* 1546 " 20546 "


15.8 1:1 .6


9.2 1:1.3


16.3 1:1.6


9.4 1:12


16.9 1:1.7


9.4 1:1.3


17.4 1:2 .0


9.5 1:14


1 5


1 2


1 5


1 2


1 7


1 2


1 8


1 3


1.0


0.9


0.r-


1.0


0.?'


0.9


O.S


0.9


TABLE 07 Condensed Ratios of the diameters of the cells and nuclei of the ganglion spirale


AVERAGE AGE


AVERAGE BODY WEIGHT


RATIOS BETWEEN TURNS


I-II


l-lll


I-IV


Cell body


Nucleus


Cell body


Nucleus


Cell body


Nucleus


days

1

8 18 13


grams 5 11 21 138


1 :0.98

0.99
1.01
0.99


1: 1.25

1.00
1.00
0 99


1:0-95

1.01
1.01
i.OI


1 : 1 . 00

1.02
1.01
1 . 00


1 : . 87

1.03

1.04

1.04


1 :0.93

1.05
1 . 05
1.02


GROWTH OF THE INNER EAR OF ALBINO RAT


129


19 M 18

17 16 15 14 13 12


10 9


Si;


DAYSi-

i i




25


50


, oo 2OO 3OO 4OO


Chart 41 'The computed diameter of the largest cell bodies and of their nuclei from the ganglion spirale, according to the turns of the cochlea, table 96. Upper graphs: diameters of the coll bodies. Lower graphs: diameters of the nuclei of the cells.


130


Figure 13 illustrates semidiagrammatically the nerve cells in the spiral ganglion of the albino rat at 1 day and at 20 and 366 days.

The body of the ganglion cells at birth is small and has the characteristic fetal form. The cytoplasm is homogeneous and scanty and the Nissl bodies are not yet seen. The nucleus forms


TABLE 98


Comparison according to sex of the diameters of the cell bodies and the nuclei in

the ganglion spirale


AGE


BODY WEIGHT


NO. OF RAT8


SEX


COMPUTED DIAMETERS M


Cell


Nucleus


days


grams






3


7


1


&


11.4


8.0



8


1


9


11.4


8.0


6


11


2


tf


13.1


8.5



10


2


9


12.8


8.4


9


10


2


c?


13.6


8.5



9


2


9


13.5


8.6


12


14


2


c? 1


13.7


8.5



12


2 .


9


13.9


8.4


100


146


. 1


<?


17.2


9.6



103


1


9


16.9


9.4


150


189


1


d 1


16.5


9.1



154


1


9


17.1


9.1


365


205


1


d 1


16.3


9.0



170


1


9


16.7


9.1


Average male


14.5


8.7


Average f e male


14.6


8.7


Male larger than female


3


3


Female larger than male


3


2


Male and female equal


1


2


the greater part of the cell. The chroma tin is not yet well differentiated, and the so-called 'Kernfaden' are not visible.

The sharply marked nucleolus is in most cases in the central position, but sometimes located peripherally.

The cytoplasm matures rapidly. At six days the Nissl bodies appear, though they are of course, less abundant and smaller than in the later stages. The nucleus develops also and the chromatin is well differentiated. Thus the development in both the cell body and the nucleus proceeds rapidly in the earlier stage.



20 Days


13



366 Days


Fig. 13 Showing semi-diagrammatically the size and the morphological changes in the ganglion cells in the ganglion spirale of the albino rat at the age of 1, 20 and 366 days. All cell figures have been uniformly magnified 1000 diameters.


GROWTH OF THE INNER EAR OF ALBINO RAT


131


At twenty days the cell body reaches its maximum size. The Nissl bodies are large and abundant. The nucleus also attains

TABLE 99

Comparison according to side of the cell bodies and their nuclei in the ganglion

spirale


AGE




SIDE


COMPUTED I.I \ M K r Ml- ft




Cell


Nucleus


days


grams






1


5


2


R.


10.6


8.0





L.


10.4


7.8


3


7


1


R.


11.4


8.0





L.


11.5


8.0


6


11


2


R.


13.0


8.5





L.


12.9


8.4


9


9


2


R.


13.4


8.5





L.


13.7


8.6


12


12


1


R.


13.9


8.4





L.


14.0


8.4


15


13


1


R.


14.7


8.6





L.


14.8


8.5


20


29


2


R.


18.0


10 1





L.


18.5


10.2


25


36


2


R.


17.6


10.1





L.


17.7


10 1


50


59


2


R.


17.5


9.9





L.


17.5


9.8


100


102


2


R.


16.8


9.5



123



L.


17.0


9.5


150


189


1


R.


16.4


9.2





L.


16.5


9.1


257


137


2


R.


17.1


9.7





L.


16.6


9.5


367


175


2


R.


17.3


9.7


365


188



L.


16.5


9.1


546


255


2


R.


16.9


9.3





L.


16.9


9.9


Average right side Average left side Right larger than left Left larger than right Right and left equal


15.3 ir>.:j 4 8 2


9.1 '.M) 7 2 5


its maximum size at this age, though the rate of increase is slower than that for the cell body. With this increase of size the his- tological structure becomes that of the adult rat. Then, as the


132


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


age advances, the size of both the cell body and of the nucleus slowly diminishes, while within the cytoplasm the differentiation of the Nissl bodies progresses. This relation is seen in the figure of the cell at 366 days, which shows that the absolute volume of the cell body and also of the nucleus is smaller than at twenty days.

From twenty to 366 days, gradual and progressive changes in all histological structures can be seen, though there are no sudden changes.


TABLE 100


Diameters of the cell bodies and their nuclei in the ganglion spirale in cross sections

of the cochlea (chart 4%)




DIAMETERS IN M


AGE


BODY


Cell body


Nucleus




Long


Short


Computed


Long


Short


Computed


days


grams








15


20


15.7


14.3


15.0


9.3


8.4


8.8


20


27


18.3


16.6


17.4


10.3


10.0


10.1


25


39


18.0


16.6


17.3


10.1


9.8


9.9


100


95


17.6


16.2


16.9 '


9.9


9.5


9.7


150


169


17.4


16.0


16.7


9.8


9.1


9.4


371


220


16.5


15.8


16.2


9.5


8.6


9.0


Ratios 15 25 days



1 1.1




1 1.1


15371 "



1.1




1.0


25371 "



1.0




0.9


The question here arose whether this change in volume was in any way related to a shift in the long axis of the cell at the later ages. To answer this difficult question it was deemed desirable to compare the form of the ganglion cells obtained in the cross-section with that found in the radial section of the cochlea. In table 100 (chart 42) are given the values for the diameters of the cell bodies and their nuclei in the ganglion spirale in the cross-section. Below are given the respective ratios from 15 to 25, 15 to 371, and 25 to 371 days. Both cell body and nucleus increase in size up to twenty days and then diminish very slowly, as the age advances. These are similar to the relations found in the radial sections.


GROWTH OF THE INNER EAR OF ALBINO RAT


133


Looking at the diameters of the cell bodies and their nuclei in each turn (table 101), we do not find in the later age groups a regular increase in passing from the base toward the apex, as in the cells on the radial section. The differences are generally

TABLE 101

Diameter of the cell bodies and their nucki in the ganglion spirale according to the turns of the cochlea (cross section)





TURNS OV THE COCHLEA


AGE


BODT WEIGHT



I


II


ill


IV





Computed diameters ft




Cell body


Nucleus


Cell body


Nucleus


Cell body


Nucleus


Cell body


Nucleus


days 15


grams 20


15.0


8.7


14.7


8.8


14.9


8.9


14.9


9


20


27


16.7


9.7


17.2


10.0


17.5


10.1


18.1


10 6


25 100


39 95


16.9 17.2


10.0 10.0


17.2 16.9


9.9 9.6


17.6 16.7


9.8 9.6


17.3 16.8


10.0 9 6


150


169


17.0


9.9


16.6


9.3


16.6


9.4


16.4


9 1


371 Ratio 15-


220 371 days


16.2 1:1.1


9.6 1:1.1


16.2 1:1.1


9.1 1:1.0


16.0 1:1.1


8.7 1:1.0


16.3 1:1.1


9.0 1:1.0


20


15


10



AGE DAYS-


O


25


50


Chart 42 The average diameter of the largest cell bodies and of their nuclei of the nerve cells from the ganglion spirale, after 15 davs (cross-section) table 100.

Cell bodies. -.-.-.-.-. Nuclei.


134 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON

far smaller than on the radial section. This result seems to have some connection with the position of the long axis of the ganglion cells in relation to the axis of the cochlea.

Comparing the diameters of the cell bodies and their nuclei in nearly corresponding places in the radial and cross-section, the long diameters of the cells are in each age group almost always larger in the radial than on the cross-section. Therefore the cells are somewhat ovoid. The short diameters, however, are at the same age sometimes longer, sometimes shorter on the radial than on the cross-sect on. This is probably due to the fact that in the upper turns the cells stand with their long diameter more nearly parallel to the axis of the modiolus, and therefore, on passing from the upper to the lower turn, the long axes of the cells become more inclined to the modiolus.

In order to show that the cell form is ovoid, I reconstructed the cells at 15, 100, and 365 days of age by the usual method, and obtained models which agreed in form with that determined by the microscope.

It appears, therefore, that while there is some difference in the diameters of these cells according to the plane of the section, neverthless, the change in volume after twenty days is similar in both cases, and so this change does not depend on the plane in which the sections were made.

On the nucleus-plasma relations of the cells in the ganglion spirale. The computed diameters of the cell bodies and their nuclei, measured on radial sections, are given in table 102 and the nucleus-plasma ratios have been entered in the last column. The ratio is at one day only 1:1.3 and increases rapidly and regularly till twenty days; after that period there are slight fluc- tuations. Generally speaking, the ratios increase with the ad- vancing age of the rat, but after twenty days only very slightly. Thus we see that the nucleus-plasma relation nearly reaches an equilibrium at twenty days, though the cells mature slowly even after that time.

When we consider this relation according to the turns of the cochlea, we find that this ratio increases in all the turns regularly and definitely till twenty days, after which there are some


GROWTH OF THE INNER EAR OF ALBINO RAT


fluctuations (table 103). Thus we see here also the same relation as before.


TABLE 102 Nucleus-plasma ratios of cells in the ganglion spirale (radial-vertical section)


AGE


BODY WEIOHT


BOOT LENGTH


COMPUTED DIAMETERS M


Cell body


Nucleus


N ucleus-plasma ratios


days


grams


mm.





1


5


48


10.5


7.9


1 : 1.3


3


8


56


11.5


8.0


2.0


6


11


63


12.9


8.4


2.6


9


10


58


13.6


8.5


3.1


12


13


60


13.8


8.5


3.3


15


13


75


14.9


8.7


4.0


20


29


95


18.1


10.2


4.6


25


36


104


17.7


10.1


4.4


50


59


125


17.5


10.0


4.4


100


112


159


16.9


9.5


4.6


150


183


190


16.7


9.2


5.0


257


137


175


16.8


9.6


4.4


366


181


191


16.9


9.4


4.8


546


255


213


16.9


9.4


4.8


TABLE 103

Nucleus-plasma ratios of cells in the ganglion spirale according to the turns of the cochlea. Based on table 96


AQB


BODY WEIOHT


TURNS Or THE COCHLEA


I


ii


in


IV


days


grama






1


5


1 :1.6


1 :1.5


1 :1.2


1 : 1.2


3


8


2.1


2.1


2.1


1.7


6


11


2.6


2.6


2.6


2.7


9


10


3.1


2.9


3.0


3.0


12


13


3.7


3.6


3.1


3.4


15


13


4.1


4.3


3.9


3.2


20


29


4.5


4.6


4.6


5.1


25


36


4.0


4.5


4.3


4.7


50


59


4.6


4.6


4.5


4.6


100


112


4.5


4.8


4.4


4.5


150


183


5.0


4.9


5.1


5.5


257


137


4.3


4.6


4.3


4.4


366


181


4.8


4.7


5.2


5.1


546


255


5.1


4.2


4.8


5.1


136


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


In the nucleus-plasma ratio of the cells on the cross-section, as shown in table 104, the increase with age is very regular. As the diameters of the cell bodies and their nuclei decrease slowly after twenty days, this increase of the ratio means that the nuclei are diminishing relatively more rapidly than the cytoplasm.

Comparing these ratios from the radial and cross sections, we find that they agree (table 105) .

TABLE 104

Nucleus-plasma ratios of the cells in the ganglion spirale (cross-sections)





COMPUTED DIAMETERS M




BODY LENGTH



AGE


BODY WEIGHT









Cell body


Nucleus


Nucleus-plasma ratios


days


grams


mm.





15


20


84


15.0


8.8


1 4.0


20


27


93


17.4


10.1


4.1


25


39


114


17.3


9.9


4.3


100


95


152


16.9


9.7


4.5


150


169


192


16.7


9.4


4.6


371


220


206


16.2


9.0


4.8


TABLE 105

The nucleus-plasma ratios according to the plane of the section at two age periods

albino rat


AGE


NUCLEUS-PLASMA RATIO ON THE RADIAL SECTION


NUCLEUS-PLASMA RATIO ON THE CROSS SECTION


AGE


days 15


1 :4.0


1 :4.0


days 15


366


1 :4.8


1 :4.8


371


Discussion. According to the foregoing data, the maximum size of the cells in the ganglion spirale, at twenty days, is in cross-sections about 18.7 x 16.9 y. for the cell body and 10.3 x 10.0 [L for the nucleus. Both the long and short diameter of the cell body thus obtained is therefore a little less than that obtained in the radial section, while the diameters for the nu- cleus are the same.

In the literature we have not found any data for the Norway rat, but there are a few observations on the size of these cells in other mammals by Kolliker ('67) and von Ebner ('02).


GROWTH OF THE INNER EAR OF ALBINO RAT


137


Schwalbe ('87) and Alagna ('09) find these ganglion cells 25 to 30 JJL in diameter in the guniea-pig and cat.

Alexander ('99) has also reported measurements on a series of mammals, but as the size of such cells is greatly influenced by the method of preparation, and as our averages are based on the largest cells while those of other authors have been ob- tained in a different manner, it seems best not to report the other values in the literature, as they are sure to be misleading.

TABLE 106

Showing the changes with age in the diameters of the cells and the nticlei of the sjriral ganglion afnd the lamina pyrmidalis of the cerebral cortex, respectively


AGE '


CELL BODY IN THE OANQL. SPIRALS COMPUT- ED DIAM. M


CELL BODY IN THE LAMINA PYRAMID COM- PUTED DIAM.


NUCLEUS IN GANOL. SI-IK. COMP. DIAM.


NUCLEUS IN THE LAMINA PYRAM. COMP. DIAM.


AGE


days






days


1


10.5


11.4


7.9


9.4


1


20


18.1


18.7


10.2


15.7


20


546


16.9


17.0


9.4


13.8


730


Ratio be-






ratio


tween 1 and


1 : 1.7


1 :1.6


1 :1.3


1 :1.3


of Ito


20 days






20







days


Ratio be-






ratio


tween 1 and


1 : 1.6


1 : 1.5


1 :1.2


1 :1.2


of Ito


546 days






730







days


Considering the course of growth in these cells, we find it to be similar in both the spiral ganglion and the lamina pyramidalis of the cerebral cortex (rat) as reported by Sugita ('18). In the former the cells attain at twenty days of age, the time of wean- ing, their maximum size, and then diminish slowly with advancing age. The cells of the lamina pyramidalis also reach their full size at twenty days, and then diminish in the same way. There- fore, the course of the growth of both of these groups of nerve cells coincides. However, I do not know of other instances of the phenomenon. When tabulated, the relations here noted appear as in table 106.

The difference between them is only in the absolute values of the diameters of the cell bodies and especially of the nuclei,


138

the nuclei in the cells of the lamina pyramidalis being decidedly larger than in those of the spiral ganglion. The ratios of in- crease are, however, similar.

When we consider the increasing ratios of the diameters of the ganglion cells, we see a close similarity in the maximum values between the cells in the spiral and gasserian ganglion (Nittono, '20). Nevertheless while in the former the ratios from 1 to 20 and 1 to 366 days are in the cell bodies 1:1.7 and 1 : 1.6, respec- tively, in the latter the ratios for the corresponding intervals are 1: 1.43 and 1: 1.69, respectively (Nittono, '20, p. 235). In the nucleus also similar relations are to be seen in both ganglia.

As these ratios show, there is in the gasserian ganglion a definite increase in the diameters of cells and nuclei after 20 days of age; the time when the maximum is reached by the cells of the spiral ganglion. Thus the former continue to grow after growth in the latter has ceased. These results suggest that the neurons in the more specialized ganglia, like the spiral ganglion, may mature earlier than do those in the less specialized.

On the correlation between the growth of the hair cells of the papilla spiralis and of the nerve cells of the ganglion spirale. When we compare the growth changes in the hair cells with those in the ganglion cells, we find that the course of the development is similar. Both classes increase in volume from one to twenty days of age, then tend to diminish slowly the hair cells more slowly than the ganglion cells. In the ratios of increase, however, there are marked differences. Thus in table 67 (bottom of last column) the volume ratios from 1 to 20 and 20 to 546 days are 1 : 2.4 and 1 : 0.9, respectively in the hair cells, and in the ganglion cells, table 108, the ratios of the volumes in the fourth column work out for the corresponding ages as 1: 5.1 and 1: 0.8, re- spectively. In the case of the nuclei the growth changes are somewhat different. In the hair cells the nucleus grows in diameter more rapidly, and therefore reaches at nine days its maximum value and then diminishes at succeeding ages.

I have sought to determine whether there was any correlation in growth between either the entire cylindrical surface or the area of the cross-section of the hair cells, on the one hand and the volume


139


of the cells of the ganglion spirale on the other. The reason for making this comparison was the fact that Levi ('08), Busacca ('16), and Donaldson and Nagasaka ('18) have noted in the cells of the spinal ganglia of several mammals that the postnatal growth in volume was correlated with the increase in the area of the body surface, and recently Nittono ('20) has found in the rat a similar relation between the growth of the cells of thegasserian ganglion and the area of the skin of the head. On examining this problem, it is evident that the correlations thus far reported

TABLE 107

Comparison of ratios between the volumes of the cells of the ganglion spirale. nn<l ///

ratios of the area of the cylijidrical surface of the hair

cells of the organ of Corti on the maximum values


AOE


BOOT WEIGHT


VOLUME OP 1 III ClANllI.ION CELL, /'


RATIOS ON THE MAXIMUM VALUE


AKEA OF CYLINDRICAL SURFACE OF THE HAIR CF.LLH- M *


1ATIO8 ON THE MAXIMUM VALUE


days


gms.




I


5


606


3105


1 :5.12


395


723


1


1.83


3


8


796




3.90


463





1.56


6


11


1124




2.76


582





1.24


9


10


1317




2.36


648





1.12


12


13


1376




2.26


681





1.03


15


13


1732




1.79


729





0.99


20


29


3105




1.00


723





1.00


25


36


2903




1.07


691





1.05


50


59


2806




1.11


697





1.04


100


112


2527




1.23


678





1.07


150


183


2439




1.28


691





1.05


257


137


2483




1.25


689





1.05


366


181


2527




1.23


683





1.06


546


255


2527




1.23


699





1.03


apply to the postnatal growth period, and that we must consider that the functional relations of the skin are well established, even at the earliest age. The data with which we have worked in the case of the cochlea are presented in several tables (107 to 110).

In tables 107 and 108 are given the volumes of the cells of the ganglion spirale and the areas of the cylindrical surface of the hair cells. In table 107 the ratios are computed by dividing the maximum value by the values at each age, and in table 108 by dividing the values at each age by the initial value.


TABLE 108

Comparison of the ratios of the volume of the cells of the ganglion spirals with the

ratios of the area of the cylindrical surface of the hair cells of the organ of

Corti on the initial values


AGE


BOOT WEIGHT


VOLUME OF THE GANGLION

CELLS M *


RATIOS ON THE INITIAL VALUE


AREA OF THE CYLINDRICAL SURFACE OF THI HAIR CELLS M


RATIOS ON , THE INITIAL \ VALUE


days


grams




1


5


606 : 606



1


1.00


395


395



1


1.00


3


8


796




1.31



463




1.17


6


11


1124




1.85



582




1.47


9


10


1317




2.17



648




1.64


12


13


1376




2.27



681




1.72


15


13


1732




2.86



729




1.85


20


29


3105




5.12



723




1.83


25


36


2903




4.79



691




1.75


50


59


2806




4.63



697




1.76


100


112


2527




4.17



678




1.72


150


183


2439




4.02



691




1.75


257


137


2483




4.10



689




1.74


366


181


2527




4.17



683




1.73


546


255


2527




4.17



699




1.77


TABLE 109

Area of the cross-section of the inner and outer hair cells






WEIGHTED





DIAMETER OF


AVERAGE


DIAMETER OF


WEIGHTED


AGE


BODY


ONE INNER


DIAMETER OF


INNER AND


AREAS OF CROSS



WEIGHT


HAIR CELL


THREE OUTER


OUTER HAIR


SECTION OF




M


HAIR CELLS


CELLS


HAIR CELLS





M


M


M 2


days


grams






1


5


6.6


6.0


6.2


30


3


8


8.0


7.4


7.6


45


6


11


8.1


7.6


7.7


48


9


10


8.8


8.5


8.6


5S


12


13


8.5


8.3


8.4


55


15


13


8.4


7.7


7.9


50


20


29


8.8


8.2


8.4


55


25


36


8.8


8.1


8.3


55


50


59


8.8


8.2


8.4


55


100


112


8.6


8.1


8.2


53


150


183


8.5


8.3


8.4


55


257


137


8.5


8.3


8.4


55


366


181


8.8


8.4


8.5


58


546


255


8.6


8.2 | 8.3


55


GROWTH OF THE INNER EAR OF ALBINO RAT


141


I have calculated the cylindrical surface of the hair cells according to the formula for the lateral surface of a cylinder; therefore, this area equals 2 v r a (r = radius, a = height of the cylinder) . As the hair cells are more or less pointed at their lower end, the surface obtained by this formula has nearly the value of the total surface of the hair cells less that for the upper end disk.

As has been already shown, both classes of cells grow rapidly from birth to twenty days, and after that both tend to decrease slightly in volume. It is evident that during the growing period,

TABLE 110

Comparison of the ratios of the volume of the cells of the ganglion spirale with the

ratios of the areas of the cross-section of the inner and outer hair cells

of the organ of Corti


AOE

days


BODY WEIGHT

gms


VOLUME OF THE GANGLION CELLS M '


RATIOS ON THE INITIAL VALUE


AREA Or THE CROSS-SECTION OF THE HAIR CELLS


RATIOS ON THE INITIAL VALUE


1


5


606


606


1


1.00


30 :30


1


1.00


3


8



796



1.31


45



1.50


6


11



1124



1.85


48



1.60


9


10



1317



2.17


58



1 . 9


12


13



1376



2.27


55



1.83


15


13



1732



2.86


50



1.67


20


29



3105



5.12


55



1.83


25


36



2903



4.79


55



l s:;


50


59



2806



4.63


53



1.77


100


112



2527



4.17


53



1.77


150


183



2439



4.02


55



1.83


257


137



2483



4.10


55



1.83


366


181



2527



4.17


58



1.93


546


255



2527



4.17


55



1.83


from one day to the end of the record, the volumes of the ganglion cells increase more rapidly than do the cylindrical areas of the hair cells (table 108). If we seek a numerical expression of these relations, it seems best to start not with the values at birth, but with those at nine days of age when the cochlea is just beginning to function, and to extend the comparison only up to twenty days when both groups of cells have reached their maximum size. Thus at nine days (table 108) the volume of the ganglion cells is 1317 [A 3 , while at twenty days it is 3105 [A 3 , or as 1: 2.3, while the area of the cylindrical surfaces of the hair cells at the respective


142 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON

ages is 648 [x 3 and 723 [i 3 , or as 1 : 1.1, thus showing a rapid growth of the ganglion cell bodies accompanied by but slight enlargement of the hair cells.

It is evident from these ratios that the ganglion cells are increasing in volume more rapidly than the hair cells in area. It is possible that the nervus cochlearis innervates the other cells of the cochlea as well, but even if this is taken into con- sideration the general relations remain the same.

It follows from this that during the period between the earliest appearance of the functional response (nine days) and the attainment of the maximum size of the cells, the innervation of the hair cells is steadily improving, if we may infer such an improvement from the increase in the volume of the ganglion cells. After the close of this early growing period the relations are approximately fixed through the remainder of life. We do not find, therefore, in the cochlea any relation which corres- ponds to those found between the spinal ganglion cells or those of the gasserian ganglion and the associated areas of the skin during postnatal growth. This seems to indicate that in the cochlea growth is fixed or limited, while in the body as a whole it is more or less continuous, and the ganglion cells behave differently in the two cases.

In table 109 are shown the diameters of the inner and outer hair cells and their weighted diameters. In the last column is given the area of the cross-section of the hair cells.

The ratios of these areas on the initial area are shown in table 110 in comparison with the volumes of the ganglion cells on the initial volume, and indicate that from three days of age the values for the ganglion cells are increasing more rapidly than those for the area of the cross-section of the hair cells, and at twenty days the increase in the case of both elements has reached a maximum. Here, as in the case of the cylindrical surface, both elements show like phases of growth, but the increase in the volumes of the ganglion cells is much greater than the increase in the cylindrical area or cross-section of the hair cells.

As it may be desirable to use for comparison the measure- ments on the cells of the ganglion spirale as here reported, the


GROWTH OF THE INNER EAR OF ALBINO RAT


143


constants for the determinations based on 160 cells in each age group are given in . table 111 for the radial vertical sections and in table 112 for the cross-sections.

TABLE 111

A nalytical constants* giving the mean, standard deviation and coefficient of variability unth their respective probable errors for the diameters of the cells and their nuclei of the ganglion spirale in radial vertical section


AOK

days


FOR TOTAL NUMBER "K CELLS


Cell Nucleus


Mean


Standard deviation


Coefficient of variability


1


Cell


10.2 0.05


0.90 0.03


8.9 0.33



Nucleus


7.8 0.02


0.46 0.01


5.9 0.22


3


Cell


11.3 0.03


0.50 0.02


4.4 0.17



Nucleus


7.9 0.02


0.32 0.01


4.1 0.15


6


Cell


12.6 0.04


0.68 0.03


5.4 0.20



Nucleus


8.4 0.03


0.48 0.02


5.7 0.22


9


Cell


13.1 0.03


0.61 0.02


4.7 0.18



Nucleus


8.5 0.03


0.52 0.02


6.1 0.23


12


Cell


13.4 0.05


0.86 0.03


6.4 0.24



Nucleus


8.4 0.03


0.61 0.02


7.3 0.28


15


Cell


14.6 0.04


0.73 0.03


5.0 0.13



Nucleus


8.7 0.03


0.58 0.02


6.7 0.25


20


Cell


17.8 0.06


1.17 0.04


6.6 0.25



Nucleus


10.0 0.02


0.40 0.02


4.1 0.15


25


Cell


17.3 0.05


0.88 0.03


5.1 0.19



Nucleus


9.9 0.02


0.36 0.01


3.6 0.14


50


Cell


17.2 0.04


0.78 0.03


4.5 0.17



Nucleus


9.7 0.02


0.34 0.01


3.6 0.14


100


Cell


16.5 0.03


0.65 0.02


3.9 0.15



Nucleus


9.4 0.02


0.38 0.01


4.0 0.15


150


Cell


16.4 0.03


0.79 0.02


4.8 0.18



Nucleus


9.1 0.02


0.42 0.02


4.6 0.17


257


Cell


16.6 0.06


1.09 0.04


6.6 0.25



Nucleus


9.5 . 02


0.39 0.01


4.1 0.15


366


Cell


16.7 0.05


1.02 0.01


6.1 0.22



Nucleus


9.3 0.03


0.52 0.02


5.6 0.21


546


Cell


16.7 0.06


1 . 06 . 04


6.4 24



Nucleus


9.3 0.02


0.45 0.02


4.9 is


Conclusion. For the study of the growth of the nerve cells in the ganglion spirale fourteen age groups were taken and the data obtained from the 160 largest cells in each age group. Besides these, six age groups, representing six cochleas, were examined in cross-sections to determine the form of the ganglion


144


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


cells and the relation of their long axes to the axis of the cochlea. Here also the ten largest cells in each of four, nearly corre- sponding turns, were measured. We obtained the following results :

1 . As thus prepared, the ganglion cells at birth have a maximum size of 11 x 10 [i in cell body and 8.2 x 7.6 [x in nucleus. At twenty days the diameters are the largest, 18.7 x 16.9 [x in cell body and 10.3 x 10.0 [x in nucleus.

TABLE 112

Analytical constants giving the mean, standard deviation and coefficient of vari- ability with their respective probable errors for the diameters of the cells and their nuclei of the ganglion spirale, in cross-section


AGE


CeU Nucleus


FOB TOTAL NUMBER OP CELLS


Mean


Standard deviation


Coefficient of variability


days 15


Cell


14.7 0.04


0.40 0.03


2.7 0.21



Nucleus


8.9 0.04


0.34 0.03


3.8 0.29


20


Cell


17.1 0.09


0.83 0.06


4.9 0.37



Nucleus


10.0 0.06


0.58 0.04


5.8 0.44


25


Cell


17.1 0.07


0.63 0.05


3.7 0.28



Nucleus


9.8 0.03


0.30 0.02


3.1 0.23


100


Cell


16.7 0.05


0.44 0.03


2.6 0.20



Nucleus


9.6 0.04


0.36 0.03


3.7 0.25


150


Cell


16.4 0.07


0.69 0.05


4.2 0.32



Nucleus


9 . 4 . 05


. 46 . 03


4.9 0.37


371


Cell


16.0 0.06


0.55 0.04


3.5 0.24



Nucleus


9.1 0.05


0.43 0.03


4.7 0.36


2. The ganglion cells grow relatively rapidly after birth and reach at twenty days of age their maximum size. After having passed the maximum at twenty days, they diminish in size very slowly, but the internal structure matures more and more with successive age.

3. The nuclei are relatively large at birth but increase more slowly than the cell bodies do; nevertheless, they follow the same course of development as the latter. This peculiar course in the growth of the ganglion cells is similar to that followed by the cells of the lamina pyramidalis of the cerebral cortex of the rat as found by Sugita ('18)


GROWTH OF THE INNER EAR OF ALBINO RAT 145

4. Within the cochlea the cell bodies and nuclei increase their diameters from the base toward the apex, except in the earlier stages.

5. There are no evident differences in the diameters of the cell bodies and the nuclei of the ganglion cells either according to sex or side.

6. Both the cell bodies and the nuclei are immature at birth, but differentiate rapidly, and even at six days the Nissl bodies are visible. The differentiation proceeds with advancing age.

7. The ganglion cells are bipolar and oval in shape. The direction of the long axis of the cells differs according to the turn of the cochlea and in the upper turn it runs almost parallel to the axis of the modiolus but inclines more and more to the horizontal position on passing to the base.

8. The nucleus-plasma ratios of the ganglion cells increase with age in both the radial and cross-sections.

9. The increase in the volume of the ganglion cells and the area of the cross-section of the hair cells is approximately sim- ilar during the first nine days of life, but after that the ganglion cells increase relatively very rapidly. These relations are very different from those found for the spinal ganglion cells by Don- aldson and Nagasaka ('18) and for the cells of the gasserian ganglion by Nittono ('20).

The nervus cochlearis innervates not only the hair cells, but all the elements of the cochlea, and this may have some in- fluence upon this relation. It is interesting to note that the rate of increase in the cylindrical surface of the hah* cells is similar to that in the area of the cross-sections of these same cells.

II. CORRELATION BETWEEN THE INCEPTION OF HEARING AND THE GROWTH OF THE COCHLEA

The present study aims merely to compare in the rat the size of each element of the cochlea just before and just after the appearance of hearing and to ascertain the changes in the cochlea which take place during this phase. The rats which have sense of hearing show the so-called ' Ohrmuschelreflex '


146 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON

of Preyer and other responses to auditory tests. Both the guinea- pig and rat react most evidently to sounds. The former animal responds usually five to six hours after birth. In the rat, however, the development of the function is, as already stated, relatively retarded and usually first appears at about ten days of age.

To test the presence of hearing there are several methods, as for example, Preyer V Ohrmuschelreflex' and the reflex closure of the eyelid, and these I used in making my observations. As the source of the sound I selected the hand clap, a whistle (Triller-pfeife, about c 4 ) and a low sound made by drawing in the breadth with nearly closed lips (about c 1 ).

Since it is my purpose merely to determine the first appear- ance of a response to sound, it is not nescessary to carry out such refined examinations as did Hunter ('14, '15, '18) Watson ('07), and others on white rats, and Marx ('09) on the guinea- pig, nor was it necessary to use the tuning-fork which by the way is not so good for tests on animals as for those on man. Since sometimes we may have a defect of hearing in animals, as shown by many investigators, it was deemed necessary to use several sources of sound and to take care not to produce ah* currents striking the test animal or to touch it in any way. For this purpose a large sheet of glass was placed between the source of sound and the rats to be tested. While the rat was resting I suddenly produced the sound and noted whether the rat responded. When the animals already had their eyes open the test was made from behind to avoid visual reflexes.

Observations

Rats at birth show no response to auditory stimuli. Most of them respond at twelve days of age very clearly, sometimes at ten to eleven days Under certain circumstances, the time of the reflex can be rather accurately noted. For example, while in the morning at ten days no reflex was noted it was present in the evening of the same day. Fortunately, I obtained five nine-day-old rats belonging to one litter and in nearly the same condition of nourishment and developnent. One of these


GROWTH OF THE INNER EAR OF ALBINO RAT 147

responded to the test very evidently at noon on the ninth day, but the others did not. The sound which was effective was fairly intense, but to a faint and low-pitched sound this rat did not respond. In this case the external auditory canal was open. In the others there was in some a small open canal, but more or less closed by a cellular plug. In the latter cases I removed this obstruction without much difficulty or damage by washing, yet no reaction could be obtained to the stimuli. As it was to be expected, that also in the latter the reflexes would very shortly appear, all the cochleas of these young rats, both the not-hearing and hearing, were fixed by the method pre- viously described and later examined.

In chapter 1, in which I followed the growth changes in the constituents of the membranous cochlea and in its ganglion cells from birth to maturity, including ' not hearing ' and ' hearing ' rats, very evident differences were observed in rats between nine and twelve days of age. In view of this, it will be of in- terest to compare the measurements obtained from the 'not hearing' and 'hearing' rats nine days old and members of the same litter. From the differences thus obtained we can conclude concerning the developmental changes in the cochlea requisite for the first appearance of hearing, provided there are no obstacles in the sound-conducting apparatus or deficiencies in the central organ.

In table 113 are given the values for the size of the several constituents of the cochlea 'from a rat which did not hear and one which did, at nine days. The former data are the averages from four cochleas, while the latter are from two. The table shows in a striking way that where there is a significant differ- ence. The values obtained from the rat which could hear are usually larger than those of the rat which could not hear.

Among these measurements we see sometimes very marked and sometimes only slight differences. Only the radial distance between the labium vestibulare and the inner edge of the head of the inner pillar cell in the first two turns and the diameter of the nuclei of the inner and outer hair cells are in the former smaller than in the latter. In both instances, however, these smaller


148


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


TABLE 113

Comparison of the dimensions of the constituents of the cochlea in a hearing rat (H.) with those in a rat not hearing (N.) at nine days of age measurements

in micro


BAT


AGE


BODY WEIGHT


(N.) (H.)


days 9 9


grams 10 11


(N.) (H.)


1430 1434


Average


distance between two spiral ligaments



Breadth of membrana tectoria



TURN I


II


III


IV


Average



Th ids ness


(N.) (H.)


243

242


270 268


304 308


306 314


281 283



27 27


Breadth of membrana basilaris



TURN I


II


III


IV


AVERAGE


ZONA ZONA ARCUATA PECTINATA


(N.) (H.)


169 171


189 186


202 214


201 204


191 196


79 112 93 103


Distance between the habenula perforata and the outer corner of the inner hair cell



TURN I


II


III


IV


AVERAGE



(N.) (H.)


38 40


38 42


44

58


49 60


42 50


Distance between habenula perforata and the outer corner ol the outer pillar cell at foot*



TURN I


II


ill


IV


Average



(N.) (H.)


70

79


76

88


86 103


86 102


79 93


Height of greater epithelial ridge



TURN I


II


III


IV


AVERAGE



(N.) (H.)


36 42


40 43


41

48


42 50


40 46


Distance between the labium vestibulare and the habenula perforata



TURN I


II


III


IV


Average



(x.)

(H.)


83

85


108 104


137 140


145 150


118 120


GROWTH OF THE INNER EAR OF ALBINO RAT


149


TABLE 113 Continued

Distance between the labium vestibulare and the inner edge of the head of the

inner pillar cell



TURN I


II


III


IV


Average



(N.) (H.)


94

78


131

108


168 170


179 210


143 142


Height from basal plane to surface of pillar cells



TURN I


II


III


IV


AVERAGE



(N.) (H.)


32 40


33

42


35

45


36 45


34 43


Height of tunnel of Corti



TURN I


II


III


IV


AVERAGE



(N.) (H.)



20



18



14



11



16


Height of papilla spiralis at the third series of outer hair cells



TURN I


II


III


IV


AVERAGE



(N.) (H.)


28 42


28 43


27 39


28 36


28

40


Height of Hensen's cells



TURN I


II


ill


IV


AVERAGE



(N.) (H.)


20 42


23 45


23

38


24 30


23

39


Angle of lamina basilaris with plane of membrana basilaris degrees



TURN I


II


HI


IV


AVERAGE



(N.) (H.)



+7



+4



-8


7




Length of the inner and outer pillar cells



INNER

TURN I


II


III


IV


AVERAGE




(N.) (H.)


35 36


39 39


41 42


40 45


39

41



OUTER TURN I


II


III


IV


AVERAGE


WEIGHTED AVERAGE


(N.) (H.)


26 45


26

54


29 50


29 40


28 47


30 46


Volume of inner and outer hair cells



INNER: AVERAGE


OUTER: AVERAGE


WEIGHTED AVERAGE


(N.) (H.)


1798 1815


1277 1279


1407 1428


150


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


TABLE 113 Concluded Diameter of nuclei of the inner and outer hair cells



INNER: AVERAGE


OUTER: AVERAGE


WEIGHTED AVERAGE


(N.) (H.)


8.3 8.2


8.0 7.4


8.1

7.6



DEITERS' CELLS:

VOLUME M '


DIAMETER OF NUCLEI


LENGTH OF CELL BODY


PHALANGEAL PROCESS


(N.) (H.)


518 1193


7.0

7.2


14 32


22 22


Ganglion spirale: diameters computed



CELLS


NUCLEI


(N.) (H.)


13.6 13.7


8.5 8.6


values are marks of maturity. These changes in size accord with the results given in chapter 1 at twelve days of age, though there are some differences between them in the absolute values.

Figures 7 and 8 illustrate the outlines of the tympanic wall of the membranous cochlea in nine-day-old rats which could not and could hear, respectively. These figures have been drawn from the corresponding sections at the beginning of the middle turn of the cochlea and are comparable with figures 3 to 6 and 9 to 12. On comparing figures 7 and 8, the more noticeable differences appear to be the following.

The membrana tectoria is a bit longer in the hearing rat. The appearance and the position of it with reference to the surface of the papilla spiralis is also different. In the not-hearing cochlea it has an infantile look.

The outer end of the main part does not yet reach the second row of the outer hair cells and connects with the Hensen's prominence by a thick thread. There are also many fine fibers to be seen between the basal surface of the membrane and the papilla. In the hearing rat the fine fibers are absent. The membrane reaches already the row of the outer hair cells and there is a strong connection between this part and the terminal

ame (Schlussrahmen) of the lamina reticularis by a thick

read as shown in figure 8 Thus the position of the membrane


GROWTH OF THE INNER EAR OF ALBINO RAT 151

above the papilla depends a little bit upon the increase of the length of the membrane itself, but chiefly upon other factors such as the inward shifting of the papilla. The membrana basilaris as a whole shows a small increase o" breadth in the hearing rat. The zona arcuate, however, increases much in its breadth, while the zona pectinata rather decreases. This is due to the development of the pillar cells. The base of the inner and outer pillar cell spread much on the membrane. At the same time the length of the cells, especially of the outer, increases nearly twice as much as in the not-hearing rat.

Thus the foot of the outer pillar cell moves out ward, as Bottcher ('69, 72) stated, while the inner corner of the inner pillar cell does not move in any way, as the habenula perforata stands at a fixed point. This results in a change in the form of the arch of Corti. The hitherto outward inclined arch tends to bend inward and between both inner and outer cells arises a space, the tunnel of Corti. The appearance of the tunnel seems to have some relation to hearing. The tunnel is always present in the cochleas of hearing rats. Sometimes the tunnel is present in the lower turns, but not in the upper turns in the not-hearing rats. We can say, therefore, that it probably appears through all the turns before the special function of the cochlea begins. In this way the zona arcuata of the membrana basilaris increases its breadth.

The next striking change is the rapid increase in the size of the Deiters' cells, Hensen's cells, and the resultant change of the form, with an inward shifting, of the papilla spiralis.

The Deiters' cells increase their height very rapidly; the length of the cell body becomes over twice that in the not-hearing rat, but the processus phalangeus changes only slightly. Hen- sen's cells develop also, but not so much as Deiters' cells. The papilla spiralis thus increases in height. On the other hand, the greater epithelial ridge vanishes inwards from the inner supporting cells and appears as a furrow the sulcus spiralis internus. Through the pressure of these outward-lying cells the papilla spiralis swings inward as a whole, without really moving on the membrana basilaris. The lamina reticularis


152 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


becomes inclined inward instead of outward and subtends a slight angle with the plane of the membrana basilaris. The distance from the labium vestibulare to the inner edge of the head of the inner pillar cell becomes smaller through the inward shifting of the papilla.

In the hair cells and the cells of the ganglion spirale we see a smaller difference between the hearing and not-hearing rats. Only the diameter of the nuclei of the hair cells in the hearing rat diminishes a little, as it continues to do in the adult cochlea.

All the changes just enumerated begin at the base of the cochlea and progress to the apex. Therefore we see the high and outward ascending papilla spiralis in turn I, while in the upper turns the papilla is not yet so developed, is smaller in all the constituents, and shows in general the characters of a younger and less mature cochlea conditions which disappear with age. This upper and immature part seems not to respond to the test for hearing. Indeed, my testing result is positive for sounds of high pitch, but not for low pitch. Therefore we conclude that the papilla spiralis develops functionally from base to apex and that when the papilla spiralis has developed in the basal turns, but not in the upper turns, it responds to sounds of high pitch alone.

Discussion

If we assume that our tests for hearing are trustworthy, then the differences between the size of the constituents of the cochlea in nine-day-old rats which could and could not hear will indicate what developmental changes in the cochlea of the albino rat are necessary for the appearance of the hearing reflex. Whether all the differences found by us are necessary is difficult to determine, and the problem is open for further study; but as the matter stands, our results give the closest correlation between structural changes and the appearance of function which has as yet been reported.

Kreidl and Yanase ('07) studied the differences between the not-hearing and hearing rat and summarized their results on page 509: "Kurz vor Eintritt des Horreflexes ist das Cortische


GROWTH OF THE INNER EAR OF ALBINO RAT 153

Organ im wesentlichen fertig ausgebildet. " They publish no measurements nor data. The condition of the development of the organ of Corti described as 'fertig ausgebildet' is not suffi- ciently precise.

Further, on the same page they say, "Der auffalligste und, soweit die Untersuchungen bis jetzt eregben haben, einzige Unterchied, der zwischen dem anatomischen Bild des Labyrinthes eines neugeborenen Tieres, das den Reflex eben nochnichtaufweist, und dem eines solchen, dasdenselben zum ersten Male eben erkenn- an lasst, ist der, dass beim ersteren noch ein Zusammenhang zwis- chen Cortischem Organ und Cortischer Membran besteht, beim letzteren dagegen dieser Zusammenhang bereits gelost oder gelock- ert ist." Their observation is quite different from mine. In my case the papilla spiralis shows in the development of its constituent elements pretty large differences between the not-hearing and hearing rats. Therefore it seems probable that the changes in the growth and form of the papilla just before the first appearance of the special function, take place very quickly. Also we cannot agree to then* statement concerning the relation of the membrana tectoria to the papilla spiralis. In our preparations there is still a connection of the membrane with the terminal frame of the lamina reticularis through a thick thread in the cochlea of the rat which could hear (fig. 8) and also in that of the rat which could not hear (fig. 7).

This is a point on which opinions differ. While one opinion, represented by Kishi ('07) and others, is to the effect that this connection remains through life, the other, represented by Koll- iker('67) and others, asserts the membrane projects free in the endolymph. I have never seen this connection in the adult cochlea, nor have I found such a connection of the membrane with the hairs of the hair cells, as Shambaugh ('10) described in the pig. In the young rats, at fifteen days for example, we very often see upon the terminal frame the broken remainder of this connecting thread. Whether this break arises through natural development or is the result of artificial manipulation it is hard to say. At any rate, Held's assertion ('90), that in an animal capable of hearing the membrana tectoria is never connected


154 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON

with the papilla spiralis, is not supported by my observation. That the freeing of the outer zone of the membrane is not ab- solutely necessary for the mediation of auditory impulses is demonstrated in the cochlea of birds, as shown by Hasse ('66), Retzius ('84), Sato ('17), and others. In these forms the mem- brane remains through life attached to the epithelial ridge.

My results agree with those of Hardesty ('15) on this point, though he obtained a tectorial membrane which floats free in the endolymph with its outer zone. Lane ('17) studied the cor- relation between the structure of the papilla spiralis and the appearance of hearing in the albino rat, but his description is brief and does not touch on this relation of the papilla to the tectorial membrane.

Thus the inception of hearing does not coincide with the detachment of the tectorial membrane from the papilla spiralis, but with the development of each constituent of the papilla spiralis and the membrane tectoria, as has been described. As these changes occur first at the base and then pass to the apex, the animal can perceive at first only the sounds of high pitch. One or two days later development is complete in all the turns, and then the rat can hear the sounds of lower pitch also. Thus the process of the development of the cochlea does not support the ' telephone theory' of audition, but on the contrary agrees with the conclusion that the papilla in different locations in the turns of the cochlea responds to sounds of a definite pitch, as Witt- maack ('07), Yoshii ('09), Hoessli ('12), and others have shown by experimental studies on the mammals.

Concerning the exact age of the first appearance of the function in the rat, there are several different statements. Lane ('17) found no response to sound before the twelfth day after birth, and on the sixteenth day he reports hearing well established. Kreidl and Yanase ('07) state that hearing begins in the rat at from twelve to fourteen days. My rats responded usually at ten to twelve days, but one at nine days. These differences depend in all probability on the vigor of the young during the first days of postnatal life, and it seems probable that exception- ally well-nourished young might develop precociously in this


GROWTH OF THE INNER EAR OF ALBINO RAT 155

respec t. The intensity of the stimulus is important in determining the hearing reflex, as Small ('99) has stated. In my cases the young rats responded very evidently to intense sounds, while they reacted weakly or not at all to those which were faint. Thus only the intense sounds were perceived by the rat of nine days.

Conclusions

1. The hearing reflex was never obtained in rats less than nine days of age.

2. At nine days a single rat, one of five in a litter, responded to a sharp sound like clapping the hands and to a whistle of high pitch; the other four did not respond. At the tenth day some of the four reacted, and at the twelfth day all could hear.

3. The hearing reflex probably occurs early in young rats that are vigorous and well nourished.

4. To obtain the first hearing reflexes it is necessary to have rather strong sounds of high pitch.

5. A comparison of the histological structure of the cochlea in rats of nine days, one of which could hear and the other could not, shows clear differences in its development of the cochlea. These consist not in the detachment of the tectorial membrane from the papilla spiralis, but in the degree of differentiation of the constituents of the papilla. The tectorial membrane is connected in both cases at its outer end with the terminal frame of the lamina reticularis by a thick thread. The papilla is more differentiated in the hearing rat in several characters. The tectorial membrane has reached with its outer end the outermost row of the outer hair cells, but in the not-hearing rat it has not yet reached the second row of the cells.

6. The form of the papilla and its relation to the surrounding structures, especially to the tectorial membrane, are in the hearing rat at nine days very similar to those in the rat at twelve days of age, though there are some differences between them in ab- solute size.

7. The freeing of the tectorial membrane from the papilla spiralis is not necessary to the appearance of the hearing reflex,


156 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON

but the differentiation of the papilla, its shifting inward, its change in form and position under the membrana tectoria, appear to be important.

8. Since the papilla develops from the base toward the apex, it first reaches in the lower turn a high degree of differentiation, and this part first begins to function. Therefore the rat can hear only sounds of high pitch when it first responds.

9. This result accords with that well-known fact that the papilla in the lower turn responds to sounds of a high pitch, while in the upper turn it responds to sounds of low pitch.

III. ON THE GROWTH OF THE LARGEST NERVE CELLS IN THE GANGLION VESTIBULARE

Material and technique

The material used for the present study was in a great part the same that was employed for the studies reported in chapter 1, with the addition of some new specimens as shown in table 114 and table 94. In the slides obtained in the radial vertical section we see the vestibular ganglion cells situated in a single group at the radix of the cochlea (Fig. 3 G. V.). As four ears were used in each age group, four cell groups were examined at each age. Besides these fourteen age groups, six rats used for cross-sections, in chapter 1, were also included.

The measurements were made in the same way and under the same conditions as those described earlier for the cells of the spiral ganglion. Since the ganglion vestibulare consists of two parts, the ganglion vestibulare superius and inferius, the ten largest cells were taken from each part and the results averaged.

Observations

By way of introduction I wish to say a word about equilibration in the young rat. The young just born crawl over on each other and seem to attempt to find the mothers nipples. They turn the head to and fro and roll over on the flanks, belly, or back. While resting they take their normal position or lie on the side. When turned on their backs they endeavor to regain the normal


GROWTH OF THE INNER EAR OF ALBINO RAT


157


position. The fore legs are of more use than the hind in making readjustments. The tails hang down between the hind legs.

TABLE 114

Data on rats used for the study of the cells of the ganglion vestibulare (radial section).

See also table 94


AOB


BOOT WEIGHT


BODY LENGTH


BEX


BIDE


AUDITOHT RESPONSE


days


grams


mm.





1


5


44


9


R.




4


44


9


R.




5


48


d 1


R. L.



3


9


60


<?


R. L.




8


56


9


R. L.



6


10


64


a


R.




10


64


9


R. L.




11


62


(7


R.



9


11


67


<?


R. L.


+



9


58


9


R.




10


57


tf


R.



12


13


70


d 1


R. L.


+



12


68


9


R.


+



15


72


c?


R.


+


15


13


74


d"


R. L.


+



14


75


9


R. L.


+


20


30


.96


d 1


R. L.


+



28


94


c?


R. L.


+


25


34


101


9


R. L.


+



34


100


d 1


R. L.


+


50


58


121


9


R. L.


+



43


104


(f


R. L.


+


100


146


176


c?


L.


+



103


154


9


L.


+



101


152


9


R. L.


+


150


154


184


9


R. L.


+



189


191


c?


R.


+



199


192


d 1


R.


+


260


137


162


9


R.


+



140


171


9


R. L.


+



134


178


9


R.


' +


367


205


202


rf


L.


+



170


182


9


L.


+



179


196


9


R. L.


+


546


282


222


d 1


R. L.


+



227


204


d 1


R. L.


+


At three days they move and crawl very actively. They tend to assume the normal position. When rolled over on the back or side they succeed in regaining the normal position in


158


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


a few seconds. When six days old the rats have fairly well coordinated movements. They use their fore and hind legs effectively and in the same way. When the mother 's body touches them they respond quickly by searching for the nipples.

At nine days they move much more quickly and the movements are well coordinated. .Though the eyes are still closed, they


TABLE 115

Diameters of the cells and their nuclei in the ganglion vestibulare in radial vertical section

(Chart 43)


AGE


BODY WEIGHT


DIAMETERS IN M


CELL BODY


NUCLEUS


Long


Short


Computed


Long


Short


Computed


days


grams








1


5


21.2


19.5


20.3


12.4


11.1


11.7


3


9


23.7


22.2


22.9


12.5


11.6


12.0


6


11


24.0


22.1


23.0


12.3


11.9


11.9


9


10


24.8


23.0


23.9


12.5


11.6


12.0


12


13


24.9


23.0


23.9


12.5


11.7


12.1


15


13


24.8


23.0


23.9


12.5


11.6


12.0


20


27


25.0


23.3


24.1


12.3


11.6


11.9


25


34


25.2


23.6


24.4


12.5


11.8


12.1


50


50


25.6


23.6


24.5


12.5


11.6


12.0


100


112


25.5


23.9


24.7


12.8


11.9


12.3


150


174


25.4


23.5


24.4


12.8


11.6


12.2


260


138


25.8


23.4


24.6


12.4


11.7


12.0


367


184


26.2


24.9


25.5


12.9


11.8


12.3


546


255


26.5


24.2


25.3


12.8


11.8


12.2


Ratios 1-


-367 days




1 1.3




1:1.1


1546 "




1.2




1.0


15367 "




1.1




1.0


crawl toward the object sought. When turned over on the back they regain the normal position immediately. While resting they lie on their bellies with all the legs spread well apart.

Twelve-day-old rats, though the eyes are still closed, go to and fro actively with good coordination, but are somewhat slower than the adults. The body loses its fetal red color through the development of the first hairs. After this period the rats do not differ greatly from the adult in their general behavior.


GROWTH OF THE INNER EAR OF ALBINO RAT


159


The growth changes in the ganglion cells of the ganglion vestibulare. In table 115 (chart 43) are given the values for the diameters of the cell bodies and their nuclei in the largest cells of the gang- lion vestibulare. At the bottom of the last column for the cell body and for the nucleus, respectively, are recorded the ratios at 1 to 367, 1 to 546, and 15 to 367 days. The last ratio was taken


25

a

20 15 10


  • GEDAYSH




25


50


5O 1OO 2OO 30O 4OO 5OO


Chart 43 The diameter of the largest cell bodies and of the nuclei from the ganglion vestibulare. table 115.

Cell bodies. -.-.-.-.-. Nuclei.

to facilitate a comparison with the data in table 118 which begin at 15 days.

Looking at the ratios of the cell bodies and of their nuclei from 1 to 546 days, it appears that the ganglion cells increase 1.2 in diameter, while their nuclei have only a very slight increase, and therefore the ratio is 1 : 1.0. This increase in the cell bodies is continuous from birth to old age, but after fifteen days is very slow. In the nucleus we see a slight increase at the earlier


160 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON

ages, after which the values are nearly constant. This means that after birth the size of the cell bodies and their nuclei does not increase so much as do those of the spiral ganglion cells, or, expressed in another way, the cells in the vestibular ganglion have developed earlier than those of the spiral ganglia and at birth have already attained nearly their full size.

On the comparison of the diameter of the cell bodies and their nuclei in the nerve cells of ihe ganglion vestibulare according to sex. For this purpose twelve age groups of albino rats were used. In seven cases we have two cochlea in each group in the same sex, in which the average value is recorded. In table 116 are entered the values for these diameters and at the foot of the table the data are analysed. They reveal no evidence of a significant difference in the diameters according to sex.

On the comparison of the diameters in the cell bodies and nuclei of the nerve cells in the ganglion ves ibulare according to side. For the present study fourteen age groups were employed. As indicated in table 117, the data in five instances are based on the average of two cochleas of the same side. Table 117 enables us to make the comparison of the diameters of the cell bodies and their nuclei on both sides, and the analysis of the data given at the bottom of the table shows that there is no difference in these characters according to side.

On the morphological changes in the cells of the vestibular ganglion. Figure 14 illustrates semi-diagrammatically the ganglion cells in the vestibular ganglion of the albino at birth, 20 and 367 days of age. These figures, as in the ganglion spirale, have been magnified 1000 times and the absolute values of the diameters are given in table 115.

As seen in figure 14, both the cell body and the nucleus are at birth already well developed and more precocious in their develop- ment than the cells in any of the other cerebrospinal ganglia thus far examined. The cytoplasm is relatively abundant and the Nissl bodies are present, though both of these characters become more marked later.

The nucleus is also large, the chromatin somewhat differentiated and the so-called 'Kernfaden' often occur. Generally speaking,




I Day


20 Days


14


366 Days


Fig. 14 Showing setrii-diagrammatically the size and the morphological changes in the ganglion cells in the ganglion vestibulare of the albino rat at the age of 1, 20 and 366 days. All cell figures have been magnified 1000 diameters.


GROWTH OF THE INNER EAR OF ALBINO RAT


161


therefore, the cells have the characteristics of the mature elements though they stain less deeply than in the adult. At twenty days of age the cell body is enlarged and fully mature. The Nissl

TABLE 116

Comparison of the diameters of the cells and their nuclei in the ganglion vestibidare

according to sex


AGE


BODY WEIGHT


NUMBER OF RATS


8EX


COMPUTED DIAMETERS


Cell body


Nucleus


days


grams






1


6


2


f


20.8


11.9





9


19.9


11.5


3


9


2


tf


21.7


11.8



8


2


9


23.8


12.2


6


11


2


tf


22.7


11.9



10


2


9


23.1


12.1


9


11


1


d*


23.8


12.5



9


1


9


23.8


12.1


12


15


1


cf


24.4


12.2



12


1


9


23.1


11.9


15


13


2


cf


24.3


12.2



13


2


9


23.4


11.9


20


30


1


cf


24.7


11.9



19


1


9


24.6


12.6


25


34


2


d"


24.4


11.9



34


2


9


24.4


12.4


50


43


2


cT


26.1


12.4



58


2


9


22.6


11.4


100


146


1


<?


26.3


12.8



103


1


9


23.4


12.6


150


194


2


rf 1


24.4


12.5



154


2


9


24.4


12.0


365


205


1


<f


24.2


11.7



170


1


9


24.6


12.1


Average for male


24.0


12.1


Average for female


23.4


12.1


Males larger


6


7


Females larger


3


5


Males and females equal


3




bodies are more differentiated and the nucleus is mature, though it shows only a slight increase in size.

At 367 days the histological structures appear much as at twenty days, but the diameters of both the cell body and the nucleus have very slightly increased. This is in contrast to the change which occurs in the cells of the spiral ganglion.


162


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


In order to study the form of the cells of the ganglion vestibulare the measurements also were made on the cross-sections. Table


TABLE 117


Comparison of the diameters of the cells and their nuclei in the ganglion vestibulare-

according to side


AGE


BODY WEIGHT


NUMBER OF RATS


SIDE


COMPUTED DIAMETERS


Cell body


Nucleus


days


grams






1


4


1


R.


20.1


12.0



5


1


L.


22.0


12.5


3


9


2


R.


23.0


11.8





L.


22.6


12.3


6


10


1


R.


23.2


12.1





L.


23.5


12.0


9


11


1


R.


25.1


12.3





L.


23.8


12.5


12


15


1


R.


24.4


12.2



13


1


L.


25.1


12.5


15


13


2


R.


24.2


12.2





L.


23.6


11.9


20


30


1


R.


24.7


11.9





L.


23.5


11.4


25


34


2


R.


23.9


12.1





L.


24.9


12.2


50


50


2


R.


23.1


11.6





L.


25.6


12.3


100


101


1


R.


25.0


12.0





L.


24.8


11.7


150


199


1


R.


25.1


12.8



154


1


L.


25.4


12.5


263


140


1


R.


26.5


12.3





L.


25.1


12.4


368


179


1


R.


27.2


12.6





L.


26.2


13.0


546


255


2


R.


26.0


12.4





L.


24.6


12.0


Average right side


24.4


12.2


Average left side


24.3


12.2


Right larger


8


6


Left larger


6


8


118 (chart 44) shows the results. Looking at the ratios of 15 to 371 days, we see the same rate of increase in the cell bodies and the nuclei as that in the radial section; i.e., in the cell bodies 1 : 1.1 and in the nuclei 1 : 1.0. Comparing the diameters at each


GROWTH OF THE INNER EAR OF ALBINO RAT


163


TABLE 118

Diameters of the cell bodies and their nuclei in the ganglion vestibulare, on cross- section (chart 44)




DIAMETERS M


AOK


BOOT WEIGHT


CELL BODY


NUCLEUS




Long


Short


Computed


Long


Short


Computed


days


grams








15


20


25.1


22.8


23.9


12.4


11.6


12.0


20


27


25.2


23.4


24.3


12.5


11.7


12.1


25


39


25.2


24.0


24.6


12.3


12.0


12.1


100


95


26.6


24.7


25.6


12.8


11.8


12.3


150


169


26.7


24.7


25.7


13.0


11.7


12.3


371


220


26.8


25.3


26.0


12.8


11.8


12.3


Ratio 15-371 days 1:1.1




1 :1.0


25


20


15


10


25


50


50 10O 20O 300 40O 5OO


Chart 44 The diameters of the cell bodies and of their nuclei from the ganglion vestibulare, after fifteen days (cross-section), table 118. Cell bodies. -.-.-.-.-. Nuclei.


164


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


age in both the radial and cross-sections, they are almost the same, with a slight tendency for the cells in the cross-section to give higher values, which suggests that the long axes of these cells tend to lie in the plane of the section.

On the nucleus-plasma relations of the ganglion cells in the gan- lion vestibulare. In table 119 are entered the computed diameters of the cell bodies and their nuclei in the radial section, and in the last column the ratios of the volume of the nucleus to that of the cytoplasm obtained by the method previously given. As

TABLE 119

Nucleus-plasma ratios of the cells in the. ganglion vestibulare radial vertical section




COMPUTED DIAMETERS M


AGE


BODY WEIGHT


Cell body


Nucleus


Nucleus-plasma ratios


days 1


grams 5


20.3


11.7


1 :4.2


3


9


22.9


12.0


5.9


6


11


23.0


11.9


6.2


9


10


23.9


12.0


6.9


12


13


23.9


12.1


6.7


15


13


23.9


12.0


6.9


20


27


24.1


11.9


7.3


25


34


24.4


12.1


7.2


50


50


24.5


12.0


7.5


100


112


24.7


12.3


7.1


150


174


24.4


12.2


7.0


260


138


24.6


12.0


7.6


367


184


25.5


12.3


7.9


546


255


25.3


12.2


7.9


seen, the ratio is at birth relatively large, 1 : 4.2, and this increases with age, in the earlier stages considerably, but in the later, less rapidly. In the oldest age group it is largest, 1: 7.9.

On the cross-section the nucleus-plasma ratio is also progressive and the increase is very regular (table 120). Comparing the ratios in the radial with those in the cross-sections, they are found to be nearly the same at fifteen twenty and twenty-five days, but at the later ages those in the cross-sections are somewhat larger than in the radial. It is difficult to determine whether the ratios on the cross-section are really larger or whether the


GROWTH OF THE INNER EAR OF ALBINO RAT


105


result depends on the fact that the number of the cells here measured is only one-fourth of that measured in the radial section, and hence fewer cells of smaller size were included. At any rate, these ganglion cells in both the radial and cross- sections of the cochlea appear to grow at about the same rate. The statistical constants for these cells and their nuclei are given in tables 121 and 122.

Discussion

The nerve cells in the ganglion vestibulare are, as seen from the above description, already well developed at birth both in size and histological structure. After that time they grow con-

TABLE 120

Nucleus-plasma ratios of cells of the ganglion vestibulare, in cross-section




DIAMETERS COMPUTED M



BOOT



AGE


WEIGHT






Cell body


Nucleus


Nucleus-plasma






ratios


days


grams





15


20


23.9


12.0


1 :6.9


20


27


24.3


12.1


7.1


25


39


24. ti


12.1


7.4


100


95


25.6


12.3


8.0


150


169


25.7


12.3


8.1


371


220


26.0


12.3


8.4


tinuously but slowly so long as followed. The increase from 1 to 546 days in the ratios of the diameters is in the cell body 1: 1.3, in the nucleus 1: 1.1, and is therefore very small. In the cerebrospinal ganglion cells and in the cells of the cerebral cortex, studied in the albino rat, there is no case which shows such a small rate of increase between birth and maturity. The follow- ing table 123 shows the ratios of increase which have been found.

It is to be noted that for the cells of the seventh spinal gang- lion and the spinal cord, the ratios were taken from 17 to 360 days. If we had the ratios from 1 to 360 days, they would be without question much larger.

There are a few measurements on the size of the ganglion cells in the vestibular ganglion of various animals in the liter-


166


ANATOMICAL AND PHYSIOLOGICAL STUDIES ON


ature. Schwalbe ('87) and Alexander ('99) report measurements on these cells in several animals, but for the reasons already given when considering the diameters of the cells in the ganglion spirale, the values obtained by the authors are not repeated here.

TABLE 121

Giving the mean, standard deviation and coefficient of variability, with their re- spective probable errors, for the diameters of the cells in the ganglion vestibulare, in radial-vertical section


AGE


CELL NUCLEUS


MEAN


STANDARD DEVIATION


COEFFICIENT OF VARIABILITY


days 1


Cell


20.1 0.16


1.46 0.11


7.3 0.55



Nucleus


11.7 0.11


0.99 0.07


8.5 0.64


3


Cell


22.6 0.14


1.33 0.10


5.9 0.44



Nucleus


11.9 0.07


0.63 0.05


5.3 0.40


6


Cell


22.8 0.13


1.23 0.09


5.4 0.41



Nucleus


11.9 0.05


0.43 0.03


3.6 0.27


9


Cell


23.6 0.16


1.48 0.11


6.3 0.48



Nucleus


12.0 0.0<9


0.82 0.06


6.8 0.52


12


Cell


23.6 0.14


1.28 0.10


5.4 0.41



Nucleus


12.0 0.06


. 59 . 04


4.9 0.37


15


Cell


23.6 0.13


1.21 0.09


5.1 0.39



Nucleus


12.1 0.06


0.60 0.05


5.0 0.38


20


Cell


23.9 0.16


1.54 0.11


6.5 0.49



Nucleus


11.9 0.10


0.90 0.07


7.6 0.55


25


Cell


24.2 0.16


1.48 0.11


6.1 0.46



Nucleus


12.1 0.08


0.74 0.06


6.1 0.46


50


Cell


24.1 0.30


2.80 0.21


11.6 0.88



Nucleus


11.8 0.09


0.86 0.06


7.3 0.55


100


Cell


24.3 0.20


1.86 0.14


7 . 7 . 58



Nucleus


12.2 0.09


0.86 0.06


7.0 0.53


150


Cell


24.1 0.18


1.70 0.13


7.1 0.53



Nucleus


12.2 0.09


0.83 0.06


6.8 0.52


260


Cell


24.3 0.26


2.45 0.18


10.1 0.76



Nucleus


11.9 0.07


0.67 0.05


5.6 0.42


367


Cell


25.2 0.22


2.07 0.16


8.2 0.62



Nucleus


12.3 0.09


0.88 0.07


7.2 0.54


546


Cell


25.0 0.19


1.80 0.14


7.2 0.54



Nucleus


12.1 0.09


0.81 0.06


6.7 0.50


On the differences between the growth of the cells in the ganglion spirale and ganglion vestibulare. The foregoing discussion has made plain that the vestibular ganglion cells grow not only in size, but also in histological structure very much before birth, while after birth they grow slowly though continuously. On the other hand, the spiral ganglion cells are relatively immature at


GROWTH OF THE INNER EAR OF ALBINO RAT


167


birth, but in the earlier stages after birth grow very rapidly, reach at twenty days their maximum size, and then diminish slowly. This great difference in the course of growth is prob- ably related to the maturity of the functions of the animal.

TABLE 122

Giving the mean, standard deviation and coefficient of variability with their respective probable errors for the diameters of the cells in the ganglion vestibulare on cross-section


AGE

days


CELL NUCLEUS


MEAN


STANDARD DEVIATION


COEFFICIENT OF VARIABILITY


15


Cell


23.8 0.21


1.00 0.15


4.2 0.58



Nucleus


12.0 0.12


0.55 0.08


4.6 0.69


20


Cell


23.9 0.20


0.92 0.14


3.9 0.58



Nucleus


12.1 0.06


0.30 0.05


2.5 0.37


25


Cell


24.4 0.20


0.94 0.14


3.9 0.58



Nucleus


12.1 0.03


0.16 0.02


1.3 0.20


100


Cell


25.4 0.32


1.51 0.23


5.9 0.90



Nucleus


12.3 0.15


0.72 0.11


5.9 0.88


150


Cell


25.6 0.20


0.94 0.14


3.7 0.55



Nucleus


12.4 0.09


0.42 0.06


3.4 0.51


371


Cell


25.9 0.41


1.91 0.29


7.4 1.11



Nucleus


12.3 0.06


0.26 0.04


2.1 0.32


TABLE 123 Ratios of diameters between the ages given.



CEREBRAL CORTEX



DONALDSON AND



(SUGITA, '18)



NAOABAKA. '18


CELL GROUP


LAMINA


LAMINA


OA88ERIAN


SPIRAL


VESTIBULAR


7TH


EFFERENT



PYHA-


GANO-


GANGLION


GANGLION


GANGLION


SPINAL


SPINAL



MIDIS


LIONARIS


NITTONO


WADA


WADA


GANGLION


CORD





C20)





CELLS


Age









days


1-730


1-730


1-330


1-546


1-546


17-360


17-360


Cell









body


1 :1.6


1 : 1.6


1 : 1.69


1 : 1.6


1 :1.2


1 :1.3


1 :1.2


Nucleus


1.5


1.5


1.20


1.2


1.0


1.2


1.2


As a consequence, in the nucleus-plasma ratio there is also a large difference between the cells in the two ganglia. Table 124 shows this.

The ratio at birth in the ganglion vestibulare is large as com- pared with that in the ganglion spirale, but the increase in this ratio


168 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON

at 546 days is relatively slight as compared with what takes place in the cells of the ganglion spirale. It appears, therefore, that the cells in the vestibular ganglion are at birth in a more mature condition.

As to the correlation between the development of the ganglion cells and the equilibrium function, we have noted that the albino rats, even just after birth, show some sense of equilibrium, though the movements are lacking in coordination. With ad- vancing age the balance of the body is held much better and all the movements gradually become coordinated. The histological structure and the size of the cells at birth suggest that they are functional at that time, and the later increase in the volume and maturity of the cells is accompanied by a corresponding

TABLE 124



GANGLION VESTIBULARE


GANGLION SPIRALE


Nucleus-plasma ratio at one day Nucleus-plasma ratio at 546 days


1 :4.8

7.9


1 : 1.3

4.2


increase in the functional development. When the tactile sense is well developed and the eyes open equilibrium is almost perfected. It is a well-known fact that these two senses have very in- timate relations to the maintenance of equilibrium. In this case, as we might expect, the early development of a function is accompanied by an early maturing of the neural mechanism on which it depends.

Conclusions (for the ganglion vestibulare)

1. The measurements were taken on the largest nerve cells of the ganglion vestibulare in the radial section of the cochlea, and the developmental changes during portnatal growth studied in fourteen age groups, comprising four ears in each group. Further, in six age groups the cell size was determined in cross- sections. The results have been given n tables 115 and 118 and charts 43 and 44.


GROWTH OF THE INNER EAR OF ALBINO RAT 169

2. The computed diameter at birth is 20.3 [x for the cell body and 11.7 ^ for the nucleus, and at 546 days, 25.3 and 12.2 n, respectively. Therefore the cells at birth are comparatively large and increase in size very slowly, but the increase is continuous.

3. The increase in the ratio of the cell body is as 1 : 1.3, of the nucleus as 1 : 1.1. We have between the same age limits no such small rate of increase in any other cerebrospinal ganglion studied in the albino rat. This small ratio indicates that the cells in the vestibular ganglion are well developed at birth.

4. We find no appreciable difference in the diameters of the cell bodies or the nuclei according either to sex or side.

5. Morphologically, the cells at birth are well differentiated. The form of the cells is ovoid.

6. The nucleus-plasma ratios are large at birth and increase regularly with age.

7. Comparing the development of the function of equilibrium with the growth of the cells, we see that these are correlated.

Final summary

This study is concerned with the age changes in the organ of Corti and the associated structures. The changes in the largest nerve cells which constitute the spiral ganglion and the vestibular ganglion, respectively, have also been followed from birth to maturity. On pages 116 to 124 are given the summary and discussion of the observations on the growth of the tympanic wall of the ductus cochlearis.

The conclusions reached from the study of the largest nerve cells in the ganglion spirale appear on pages 143 to 145. On pages 155 and 156 are presented the results of the study on the correlation between the response to sound and to the conditions of the cochlea.

Finally, the observations on the growth of the largest cells in the ganglion vestibu'are are summarized on pages 168 and 169.

It is not necessary to again state in detail the conclusions reached in the various parts of this study.

At the same time, if we endeavor to obtain a very general picture of the events and changes thus described, this may be sketched as follows:


170 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON

Within the membranous cochlea there occurs a wave of growth passing from the axis to the periphery as shown in figures 4 to 13. The crest or highest point of the tissue mass appears at birth near the axis, in the greater epithelial ridge, and then progress- ively shifts toward the periphery, so that at maturity it is in the region of the Hensen cells. With advancing age the hair cells come to lie more and more under the tectorial membrane and the pillar cells seem to shift toward the axis.

At from 9 to 12 days the tunnel of Corti appears and the rat can hear.

All of these changes occur first in the basal turn and progress toward the apex. The mature relations are established at about twenty days. There are thus two waves of change in the mem- branous cochlea, from the axis to the periphery and the other from the base to the apex. The rat can usually hear at twelve days of age or about three days before the eyes open.

The largest cells in the ganglion spirale are very immature at birth, reach their maximum at twenty days, and after that di- minish in size, slightly but steadily. The rat hears, therefore, before these cells have reached their full size.

The largest cells in the vestibular ganglion are precocious and remarkably developed, even at birth. They cease their rapid growth at about fifteen days of age, but increase very slightly though steadily throughout life.


GROWTH OF THE INNER EAR OF ALBINO RAT 171


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