Anatomical and physiological studies on the growth of the inner ear of the albino rat 2 (1923): Difference between revisions

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=Anatomical and Physiological Studies on the Growth of the Inner Ear of the Albino Rat=
=Anatomical and Physiological Studies on the Growth of the Inner Ear of the Albino Rat=
==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
LITERATURE CITED
ALAGNA, G. 1909 Beitrag zur normalen und pathologischen Histologie
der Ganglien des Akustikus. Ztscher. f. Ohrenh., Bd. 59.
ALEXANDER, G. 1899 Zur Anatomie des Ganglion vestibulare der Sauge-
thiere. Sitz.-Ber. Akad. Wiss. math. nat. Cl., Wien, Bd. 108,
Abt. 3.
AYERS, H. 1890 On the origin of the internal ear and the functions of the
semi-circular canals and cochlea. Milwaukee.
1891 Die Membrana tectoria-was sie ist, und die Membrana
basilaris-was sie verrichet. Anat. Anz., Bd. 6.
1889 On the membrana basilaris, the membrana tectoria and the
nerve endings in the human ear. Zool. Bull., vol. 1.
BARTH 1889 Beitrag zur Anatomie der Schnecke. Anat. Anz., Bd. 4.
BOTTCHER, A. 1869 Ueber Entwickelung und Bau des Gehorlabyrinthes
nach Untersuchungen an Saugethieren. F. Blockmann u. Sohn,
Dresden.
1872 Kritische Bemerkungen und neue Beitrage zur Literatur
des Gehorlabyrinths. Dorpat.
BUSACCA, A. 1916 Studi sulla curva di accrescimento delle cellule nervose
dei gangli spinali nei mammiferi. Arch. ital. di aaat. e di em-
briologia, T. 15.
CORTI, A. 1851 Recherches sur 1'organe de 1'ouie des mammiferes. Ztschr.
f. wiss. Zool., Bd. 3.
CZINNER, H. I., UND HAMMERSCHLAG, V. 1897 Beitrag zur Entwicklung-
sgeschichte der Corti'schen Membran. Archiv f. Ohrenh., Bd. 44.
DONALDSON, H. H. 1915 The rat. Reference tables and data for the albino
rat (Mus norvegicus albinus) and the Norway rat (Mus norvegicus).
Memoirs of the Wister Institute of Anatomy and Biology, no. 6.
DONALDSON, H. H., AND NAGASAKA, G. 1918 On the increase in the diameters
of nerve cell bodies and of the fibers arising from them, during the
later phases of growth (albino rat). Jour. Comp. Neur., vol. 29.
DUPUIS, A. 1894 Die Cortische Membran. Anat. Hefte, Bd. 3.
VON EBNER, V. 1902 In A. Kolliker's Hanbd. d. Gewebelehre des Menschen,
Bd. 3, 2 Halfte, S. 899-959.
EWALD, J. R. 1899 Zur Physiologie des Labyrinthes. VI. Mitteil. Eine
neue Hortheorie. Arch. ges. Physiol., Bd. 76.
EWALD, J. R. UND JADERHOLM, G. A. 1906 Auch alle Gerausche geben,
wenn sie intermittiert werden, Intermittenztone. Arch. ges. Physiol.,
Bd. 115.
GOTTSTEIN, J. 1872 Ueber den feineren Bau und die Entwickelung der
Gehorschnecke der Saugethiere und des Menschen. Arch. f. inikr.
Anat., Bd. 8.
HARDESTY, I. 1908 The nature of the tectorial membrane and its probable
rfile in the anatomy of hearing. Am. Jour. Anat., vol. 8.
1915 On the proportions, development and attachment of the
tectorial membrane. Am. Jour. Anat., vol. 18.
172 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON
HASSE, C. 1866 Die Schnecke der Vogel. ' Ztscher. f. wiss. Zool., Bd. 17.
1873 Die vergleichende Morphologic und Histologie des hautigen
Gehororganes der Wirbeltiere. Suppl. zu dem anatom. Studien
von C. Hasse, Bd. 1, Leipzig.
HELD, H. 1902 Untersuchungen fiber den feineren Bau des Ohrlabyrinths
der Wirbeltiere. I. Zur Kenntnis des Corti'schen Organs u. der
librigen Sinnesapparate des Labyrinths bei Saugetieren. Abhandl.
d. k. Sachs. Ges. d. Wiss., Math.-phys. Kl., Bd. 28.
1909 Untersuchungen tiber den feineren Bau des Ohrlabyrinths
der Wirbeltiere. II. Zur Entwicklungsgeschichte des Corti'schen
Organs und der Macula acustica bei Saugetieren und Vogeln.
Abhandl. d. k. Sachs. Ges. d. Wiss., Math-phys. Kl., Bd. 31.
HENLE, J. 1866 Handbuch d. systemat. Anatomic des Menschen. II.
Bd. Eingeweidelehre des Menschen. Braunschweig.
1873 Handbuch d. systemat. Anatomic des Menschen. II.
Bd. Eingeweidelehre des Menschen. 2. Aufl. Braunschweig,
v. HENSEN, 1863 Zur Morphologic der Schnecke, des Menschen und der
Saugetiere. Ztscher. f. wiss. Zool., Bd. 13.
1873 Dr. A. Bottcher: Ueber Entwicklung und Bau des Gehor-
labyrinths nach Untersuchungen an Saugetieren. Arch. f. Ohrenh.,
Bd. 6.
HOESSLI, H. 1912 Weitere experimentelle Studien liber die akustische
Schadigung des Saugetierlabyrinths. Ztschr. f. Ohrenh., Bd. 64.
HUNTER, W. S. 1914 The auditory sensitivity of the white rat. Jour. Animal
Behavoir, vol. 4.
- 1915 The auditory sensitivity of the white rat. Jour. Animal
Behavoir, vol. 5.
1918 Some notes on the auditory sensitivity of the white rat.
Psychobiology, vol. 1.
KATO, T. 1913 Zur Physiologic der Binnenmuskeln des Ohres. Arch. f. d.
ges. Physiol., Bd. 150.
KISHI, J. 1902 Uber den Verlauf und die periphere Endigung des Nervus
cochleae. Arch. f. mikr, Anal., Bd. 59.
KISHI, K. 1907 Cortische Membran und Tonempfindungstheorie. Arch. f.
d. ges. Physiol., Bd. 116.
v. KOLLIKER, A. 1867 Handbuch der Gewebelehre des Menschen. 5. Aufl.
Leipzig.
KOLMER, W. 1907 Beitrage zur Kenntnis des feiaeren Baues des Gehororgans
mit besonderer Beriicksichtigung der Haussaugetiere. Arch. f.
mikr. Anat., Bd. 70.
KRATJSE, F. 1906 Entwicklungsgeschichte des Gehororgans. Handb. d.
Entwicklungslehre der Wirbeltiere, Bb. 2, Teil 2. Jena.
KREIDL, A., TJND YANASE, J. 1907 Zur Physiologie der Cortischen Membran.
Zentralbl. f. Physiol., Bd. 21.
LANE, H. H. 1917 The correlation between structure and function in the
development of the special senses of the white rat. Diss. presented
to Princeton Univ. University of Oklahoma, Norman.
GROWTH OF THE INNER EAR OF ALBINO RAT 173
LEVI, G. 1908 I gangli cerebrospinali Studi di istologia comparata e di
istogenesi. Arch. Hal. Anat. Embr., T. 7, Suppl.
MARX, H. 1909 Untersuchungen uber e. \perimentelle Schadigungen des
Gehororgans. Ztschr. f. Ohrenh., Bd. 59.
METZNER AND YOSHIT 1909 Experimentelle Schadigungen des GehSrorgans
durch Schalleinwirkungen. Verb. d. Ges. deutsch Nat. Aerzte
Vers., 2. Teil. 2. Halfte.
MIDDENDORP, H. W. 1867 Het vliezig slakkenhuis in zijne wording en in
den ontwikkelden toestand. Groningen.
1868 Zur Histologie und Entwickelung der Schnecke. Monatschr.
f. Ohrenh., nos. 11 and 12.
XAGER, F. R. 1905 Uber postmortale histologische Artefakte am Nervus
acusticus und ihre Erklarung, ein Beitrag zur Lehre der Corpora
amylacea. Ztschr. f. Ohrenh., Bd. 51.
NAGER, F. R., UND YOSHII, U. 1910 Zur Kenntnis der cadaverosen Verander-
ungen des innerea Ohres. Zeitschr. f. Ohrenh., Bd. 60.
XAKAMURA, Y. 1914 Experimentelle Untersuchungen uber die Einwirkung
des Aethyl und Methylalkols auf dera Gehororgan. Beitr, z. Anat.,
Physiol., Path. u. Therap. d. Ohres, Bd. 8.
NITTONO, KENJI 1920 On the growth of the neurons composing the gasserian
ganglion of the albino rat, between birth and maturity. Jour.
Comp. Neur., vol. 32.
PRENTISS, C. W. 1913 On the development of the membrana tectoria with
reference to its structure and attachments. Am. Jour. Anat., vol. 14.
PRITCHARD, U. 1878 The development of the organ of Corti. Jour. Anat. and
Physiol., vol. 13.
RETZIUS, G. 1884 Das Gehororgan der Wirbeltiere. 11. Stockholm.
RICKENBACHER, O. 1901 Untersuchungen Uber die embryonale Membrana
tectoria des Meerschweinchens. Anat. Hefte, Bd. 16.
SATO, N. 1917 Der histologische Bau der Vogelschnecke und ihre Schadigung
durch akustische Rei/e und durch Detonation. Basel.
SCHAFER, E. A. 1909 Quain's elements of anatomy, vol. 3, part 2, llth
ed., London.
SCHWALBE, G. 1887 Lehrbuch der Anatomic der Sinnesorgane. Erlangen.
SCOTT, .SYDNEY 1909 A contribution to the histology of the human osseous
and membranous labyrinth. J. of Anat. Physiol., vol. 43, pp. 329-345.
SHAMBAUGH, G. E. 1910 Das Verhaltniss zwischen der Membrana tectoria
und dem Cortischen Organ. Ztschr. f. Ohrenh., Bd. 62.
1910 A The physiology of the cochlea. Ann. Otol. Rhinol. and
Laryngol., vol. 19.
1910B The physiology of tone perception. Ann. Otol. Rhinol. and
Laryngol., vol. 19.
SIEBENMANN UND YOSHII 1908 Praparate von zirkumskripter Labyrinthitis.
Verhandl. der Deutsch. otolog. Gesellsch.
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.
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==III. On the growth of the largest nerve cells in the ganglion spirale==
==III. On the growth of the largest nerve cells in the ganglion spirale==

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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. Rat Inner Ear (1923): I. Cochlea growth | II. Inception of hearing and cochlea growth | III. Growth of largest nerve cells in ganglion vestibulare | Final Summary | Literature Cited

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Anatomical and Physiological Studies on the Growth of the Inner Ear of the Albino Rat

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


LITERATURE CITED

ALAGNA, G. 1909 Beitrag zur normalen und pathologischen Histologie

der Ganglien des Akustikus. Ztscher. f. Ohrenh., Bd. 59. ALEXANDER, G. 1899 Zur Anatomie des Ganglion vestibulare der Sauge-

thiere. Sitz.-Ber. Akad. Wiss. math. nat. Cl., Wien, Bd. 108,

Abt. 3. AYERS, H. 1890 On the origin of the internal ear and the functions of the

semi-circular canals and cochlea. Milwaukee.

1891 Die Membrana tectoria-was sie ist, und die Membrana

basilaris-was sie verrichet. Anat. Anz., Bd. 6.

1889 On the membrana basilaris, the membrana tectoria and the nerve endings in the human ear. Zool. Bull., vol. 1.

BARTH 1889 Beitrag zur Anatomie der Schnecke. Anat. Anz., Bd. 4. BOTTCHER, A. 1869 Ueber Entwickelung und Bau des Gehorlabyrinthes

nach Untersuchungen an Saugethieren. F. Blockmann u. Sohn,

Dresden.

1872 Kritische Bemerkungen und neue Beitrage zur Literatur

des Gehorlabyrinths. Dorpat. BUSACCA, A. 1916 Studi sulla curva di accrescimento delle cellule nervose

dei gangli spinali nei mammiferi. Arch. ital. di aaat. e di em-

briologia, T. 15. CORTI, A. 1851 Recherches sur 1'organe de 1'ouie des mammiferes. Ztschr.

f. wiss. Zool., Bd. 3. CZINNER, H. I., UND HAMMERSCHLAG, V. 1897 Beitrag zur Entwicklung-

sgeschichte der Corti'schen Membran. Archiv f. Ohrenh., Bd. 44. DONALDSON, H. H. 1915 The rat. Reference tables and data for the albino

rat (Mus norvegicus albinus) and the Norway rat (Mus norvegicus).

Memoirs of the Wister Institute of Anatomy and Biology, no. 6. DONALDSON, H. H., AND NAGASAKA, G. 1918 On the increase in the diameters

of nerve cell bodies and of the fibers arising from them, during the

later phases of growth (albino rat). Jour. Comp. Neur., vol. 29. DUPUIS, A. 1894 Die Cortische Membran. Anat. Hefte, Bd. 3. VON EBNER, V. 1902 In A. Kolliker's Hanbd. d. Gewebelehre des Menschen,

Bd. 3, 2 Halfte, S. 899-959. EWALD, J. R. 1899 Zur Physiologie des Labyrinthes. VI. Mitteil. Eine

neue Hortheorie. Arch. ges. Physiol., Bd. 76. EWALD, J. R. UND JADERHOLM, G. A. 1906 Auch alle Gerausche geben,

wenn sie intermittiert werden, Intermittenztone. Arch. ges. Physiol.,

Bd. 115. GOTTSTEIN, J. 1872 Ueber den feineren Bau und die Entwickelung der

Gehorschnecke der Saugethiere und des Menschen. Arch. f. inikr.

Anat., Bd. 8. HARDESTY, I. 1908 The nature of the tectorial membrane and its probable

rfile in the anatomy of hearing. Am. Jour. Anat., vol. 8.

1915 On the proportions, development and attachment of the

tectorial membrane. Am. Jour. Anat., vol. 18.


172 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON

HASSE, C. 1866 Die Schnecke der Vogel. ' Ztscher. f. wiss. Zool., Bd. 17.

1873 Die vergleichende Morphologic und Histologie des hautigen

Gehororganes der Wirbeltiere. Suppl. zu dem anatom. Studien

von C. Hasse, Bd. 1, Leipzig. HELD, H. 1902 Untersuchungen fiber den feineren Bau des Ohrlabyrinths

der Wirbeltiere. I. Zur Kenntnis des Corti'schen Organs u. der

librigen Sinnesapparate des Labyrinths bei Saugetieren. Abhandl.

d. k. Sachs. Ges. d. Wiss., Math.-phys. Kl., Bd. 28.

1909 Untersuchungen tiber den feineren Bau des Ohrlabyrinths

der Wirbeltiere. II. Zur Entwicklungsgeschichte des Corti'schen

Organs und der Macula acustica bei Saugetieren und Vogeln.

Abhandl. d. k. Sachs. Ges. d. Wiss., Math-phys. Kl., Bd. 31. HENLE, J. 1866 Handbuch d. systemat. Anatomic des Menschen. II.

Bd. Eingeweidelehre des Menschen. Braunschweig.

1873 Handbuch d. systemat. Anatomic des Menschen. II.

Bd. Eingeweidelehre des Menschen. 2. Aufl. Braunschweig, v. HENSEN, 1863 Zur Morphologic der Schnecke, des Menschen und der

Saugetiere. Ztscher. f. wiss. Zool., Bd. 13.

1873 Dr. A. Bottcher: Ueber Entwicklung und Bau des Gehor-

labyrinths nach Untersuchungen an Saugetieren. Arch. f. Ohrenh.,

Bd. 6. HOESSLI, H. 1912 Weitere experimentelle Studien liber die akustische

Schadigung des Saugetierlabyrinths. Ztschr. f. Ohrenh., Bd. 64. HUNTER, W. S. 1914 The auditory sensitivity of the white rat. Jour. Animal

Behavoir, vol. 4. - 1915 The auditory sensitivity of the white rat. Jour. Animal

Behavoir, vol. 5.

1918 Some notes on the auditory sensitivity of the white rat.

Psychobiology, vol. 1. KATO, T. 1913 Zur Physiologic der Binnenmuskeln des Ohres. Arch. f. d.

ges. Physiol., Bd. 150. KISHI, J. 1902 Uber den Verlauf und die periphere Endigung des Nervus

cochleae. Arch. f. mikr, Anal., Bd. 59. KISHI, K. 1907 Cortische Membran und Tonempfindungstheorie. Arch. f.

d. ges. Physiol., Bd. 116. v. KOLLIKER, A. 1867 Handbuch der Gewebelehre des Menschen. 5. Aufl.

Leipzig. KOLMER, W. 1907 Beitrage zur Kenntnis des feiaeren Baues des Gehororgans

mit besonderer Beriicksichtigung der Haussaugetiere. Arch. f.

mikr. Anat., Bd. 70. KRATJSE, F. 1906 Entwicklungsgeschichte des Gehororgans. Handb. d.

Entwicklungslehre der Wirbeltiere, Bb. 2, Teil 2. Jena. KREIDL, A., TJND YANASE, J. 1907 Zur Physiologie der Cortischen Membran.

Zentralbl. f. Physiol., Bd. 21. LANE, H. H. 1917 The correlation between structure and function in the

development of the special senses of the white rat. Diss. presented

to Princeton Univ. University of Oklahoma, Norman.


GROWTH OF THE INNER EAR OF ALBINO RAT 173

LEVI, G. 1908 I gangli cerebrospinali Studi di istologia comparata e di

istogenesi. Arch. Hal. Anat. Embr., T. 7, Suppl. MARX, H. 1909 Untersuchungen uber e. \perimentelle Schadigungen des

Gehororgans. Ztschr. f. Ohrenh., Bd. 59. METZNER AND YOSHIT 1909 Experimentelle Schadigungen des GehSrorgans

durch Schalleinwirkungen. Verb. d. Ges. deutsch Nat. Aerzte

Vers., 2. Teil. 2. Halfte. MIDDENDORP, H. W. 1867 Het vliezig slakkenhuis in zijne wording en in

den ontwikkelden toestand. Groningen.

1868 Zur Histologie und Entwickelung der Schnecke. Monatschr.

f. Ohrenh., nos. 11 and 12. XAGER, F. R. 1905 Uber postmortale histologische Artefakte am Nervus

acusticus und ihre Erklarung, ein Beitrag zur Lehre der Corpora

amylacea. Ztschr. f. Ohrenh., Bd. 51. NAGER, F. R., UND YOSHII, U. 1910 Zur Kenntnis der cadaverosen Verander-

ungen des innerea Ohres. Zeitschr. f. Ohrenh., Bd. 60. XAKAMURA, Y. 1914 Experimentelle Untersuchungen uber die Einwirkung

des Aethyl und Methylalkols auf dera Gehororgan. Beitr, z. Anat.,

Physiol., Path. u. Therap. d. Ohres, Bd. 8. NITTONO, KENJI 1920 On the growth of the neurons composing the gasserian

ganglion of the albino rat, between birth and maturity. Jour.

Comp. Neur., vol. 32. PRENTISS, C. W. 1913 On the development of the membrana tectoria with

reference to its structure and attachments. Am. Jour. Anat., vol. 14. PRITCHARD, U. 1878 The development of the organ of Corti. Jour. Anat. and

Physiol., vol. 13.

RETZIUS, G. 1884 Das Gehororgan der Wirbeltiere. 11. Stockholm. RICKENBACHER, O. 1901 Untersuchungen Uber die embryonale Membrana

tectoria des Meerschweinchens. Anat. Hefte, Bd. 16. SATO, N. 1917 Der histologische Bau der Vogelschnecke und ihre Schadigung

durch akustische Rei/e und durch Detonation. Basel. SCHAFER, E. A. 1909 Quain's elements of anatomy, vol. 3, part 2, llth

ed., London.

SCHWALBE, G. 1887 Lehrbuch der Anatomic der Sinnesorgane. Erlangen. SCOTT, .SYDNEY 1909 A contribution to the histology of the human osseous

and membranous labyrinth. J. of Anat. Physiol., vol. 43, pp. 329-345. SHAMBAUGH, G. E. 1910 Das Verhaltniss zwischen der Membrana tectoria

und dem Cortischen Organ. Ztschr. f. Ohrenh., Bd. 62.

1910 A The physiology of the cochlea. Ann. Otol. Rhinol. and

Laryngol., vol. 19.

1910B The physiology of tone perception. Ann. Otol. Rhinol. and

Laryngol., vol. 19. SIEBENMANN UND YOSHII 1908 Praparate von zirkumskripter Labyrinthitis.

Verhandl. der Deutsch. otolog. Gesellsch. 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.


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III. 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 measurements, 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 approximate 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 according 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 histological 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 fluctuations. Generally speaking, the ratios increase with the advancing 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 nucleus 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 obtained 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 COMPUTED DIAM. M


CELL BODY IN THE LAMINA PYRAMID COMPUTED 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 weaning, 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. Therefore, 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 increase 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, respectively, 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, respectively. 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 consideration 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 corresponds 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 measurements 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 corresponding 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 variability 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 similar 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 Donaldson 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 influence 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.

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