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=A Contribution to the Development of the Prostate in Man=
ic EA CONTRIBUTION TO THE DEVELOPMENT OF THE PROSTATE
IN MAN. By EVELYN JOHN EVATT, University College, Cardifi”.
 
IN connection with this contribution I desire to thank Professor’
 
Wiedersheim of the Anatomical Institute, Freiburg in Breisgau, for the
generous way in which he placed the facilities of his department at my
disposal;'and I also wish to acknowledge my indebtedness to Professor
Keibel for the very helpful advice I received from him during the construction of a wax-plate model of the glandular tissue of the prostate. The
following conclusions regarding the development of the prostate have been
arrived at chiefly from a study of this model and of the sections from
which the model was built up.
 
The foetus from which the prostate Was taken was said to be three and
a half months old. It measured 12 cm. from vertex to coccyx. The foetus
was injected through the umbilical vein with a_ 10 per cent. solution of
formalin. The sections, which were 12 micro-millimetres thick, were
stained with picrocarmine. The model represents a magnification of 64.
When the model was fully constructed it was split down, just a little to
the left of the middle line, so as to leave the anterior ducts associated
with the right half. The short transverse lines in figs. 2 and 3 indicate
the plane along which it was split. In the model the ducts represent the
Whole thickness of the epithelial walls of the original ducts. This was done
because one could not always recognise the lumen of every duct, and further,
because the outline of the epithelial buds was sharply demarcated from the
surrounding tissues, and could therefore be accurately traced. In the case of
the prostatic urethra the inner wall was traced, so that the model represents,
as it were, a cast of the inside of the prostatic urethra with the prostatic
ducts in their whole thickness attached to it.
 
In the course of this paper I shall suppose the foetus to be in the
anatomical posture, and employ the terms superior and inferior, anterior
and posterior, in the sense in which they are used nowadays.
 
The prostatic urethra at this stage of development, three and a half
months, consists of two parts: (1) an upper fourth, and (2) a lower threefourths (figs. 2 and 3, U.S. and L.S.). Just near the neck of the bladder the
urethra has the shape indicated in fig. 5 on transverse section; a little lower
down it takes on the form seen in fig. 6. These two outlines represent the
form of the upper fourth of the urethra at its upper and lower ends.
' A Contribution to the Development of the Prostate in Man 315
 
Different views of the two halves of a wax-plate model of the rostatic urethra and glandular tissue of the
prostate. The short transverse lines in figs. 2 and 3 in icate the plane along which the model was
split. Figs. 1 and 2, outer and inner surfaces of the right half respectively. Figs. 3 and 4, inner and
outer surfaces of the left half respectively.
 
U.S., up r subdivision ; L.S., lower subdivision: U., urethra; A.D., anterior ducts ; I.lI.D., inferior horizontal ducts;
3r L.D.. ducts of the “3rd lobe ”; W.D., Wolflian ducts; V.S., vesicular seminnles ; M.D., Miillerian ducts.
316 Mr Evelyn John Evatt
 
THE LOWER SUBDIVISION OF THE PROSTATIC URETHRA is spur-shaped on
transverse section (fig. 7); the difference in shape is associated with the
presence of the crista urethralis in the lower three-fourths.
 
The Wolffian and Miillerian ducts (genital cord) enter the lower subdivision at the junction of its upper and middle thirds (figs. 2 and 3, M.D.
and W.D.) ‘
 
The arrangement of the ducts arising from the lower subdivision.
 
Four ducts grow out from the anterior limb of the urethra; they are all
directed upwards, and do not branch (figs 1 and 2, AD.).
 
 
FIG. 5.—Section through the prostate and genital cord at the
upper end of the “ upper subdivision ” of the prostate.
 
Pr., prostate; G.C., genital cord ; U., cavity of the urethra ; A.D., P.D.,
 
L.D., anterior posterior, and lateral prostatic ducts respectively;
W. D. (V .S.), Wolfilan ducts(vesicu1aa seminales).
 
The ducts which come off from the bottom of the prostatic sinus are
nine in number on each side; they arise at intervals along its whole length ;
they pass backwards for a short distance, and then turn upwards, branching
frequently and irregularly. The upper ones are larger and more branched
than the lower, being apparently in a more advanced stage of development
(figs. 1 and 4:).
 
Seven ducts pass out from the outer wall of each sinus; the more anterior
of these are unbranched (figs. 1 and 4:). They all pass upwards.
 
Three ducts, the inferior horizontal, arise from the internal wall of
each sinus, below the point of entrance of the genital cord; they pass
directly backwards, branching frequently (figs. 2 and 3, I.H.D.). They
‘A Contribution to the Development of the Prostate in Man 317
 
are remarkable in that they are the only ducts which do _ not pass
upwards.
N o ducts grow out from the summit of the crista urethralis.
 
UPPER SUBDIVISION 013‘ THE PROSTATIC URETHRA (figs. 2 and 3, U.S.).
 
Three ducts take origin from the anterior limb or angle (figs. 1 and 2);
they are short, and of considerable thickness; they pass upwards and do
not branch.
 
 
FIG. 6.—Ti-ansverse section throu h the middle of the
“upper subdivision ” of t e prostate.
 
l-7., urethra; A.D., L.D., anterior and lateral prostatlc ducts
 
respectively ; P.D., posterior prostatic ducts (those of the
3rd lobe) ; W.D., Wolfllnn ducts.
 
Four ducts arise from the outer wall on each side; they lie in series with
the lateral ducts of the lower subdivision (figs. 1 and 4).
 
The two largest ducts of the prostate arise one from each postero—
external angle of the urethra (figs. 2 and 3, 3rd L.D.). They first pass downwards for a short distance and then turn upwards, branching frequently
and irregularly, their branches nearly touching in the middle line behind.
They seem to have been first observed by Henle, though later observers
 
apparently failed to find them. They may be termed the ducts of the
third lobe. Two small unbranched ducts arise in series with these, and on
 
a higher plane, and pass upwards: there are thus fifty—nine ducts in all.
At first sight it Would seem that the anterior ducts are unpaired, and
318 Mr Evelyn John Evatt
 
were not bilaterally symmetrical, but an examination of the transverse
sections of the prostate appears to reveal the true history of these ducts;
for instance, a transverse section through the middle of the prostate shows
two ducts springing from the anterior wall of the urethra (fig. 8, A); higher’
up the appearance is as in fig. 8, B ; fig. 8, C, is still higher; and finally, fig.
8, D, shows only one duct. These sections would seem to show that
originally on the right side there were ducts corresponding with those on
the left, and that the latter assumed a mesial position owing to the former
not going on to further development.
 
 
FIG. 7. ——Transverse section through the “lower subdivision ” of the prostate in the neighbourhood of the Wolffian and Miillerian ducts.
 
W.D., Wolflian ducts; M. D., Miillerlan ducts; U.. urethra; A.D., P.D., anterior
and posterior prostntic ducts respectively ; LD. and S.D.. lateral ducts.
 
THE LOBES or THE PROSTATE.
 
At first the prostatic sinuses and their ducts in the lower subdivision are
widely separated (figs. 7 and 8). The ducts from the bottom of each sinus,
together with those which grow out from the lateral walls of each sinus, may
be regarded as forming the lateral lobe of that sinus. The branches of the
ducts from the bottom and outer Wall of one sinus probably do not meet those
of the other side behind, though the branches of the ducts from the inner
walls of the sinus (the inferior horizontal ducts, figs. 2 and 3, I.H.D.) do so.
 
The branches of the two largest ducts (the ducts of the third lobe, figs.
2 and 3, 3rd L.D.) come together in the middle line behind, and these with
the two smaller ducts immediately above them form a centrally placed
A Contribution to the Development of the Prostate in Man 319
 
lobe above the level of the point of entrance of the genital cord. This is
the third lobe; it consists of ducts derived from both sides of the prostate,
and cannot therefore be regarded as an azygos structure.
 
Development of the Ducts.——Certain of these are formed by a pinching
oil" of a portion of the urethral lining membrane in its long axis. This
fold or tuck eventually separates from the urethra, except at its lower end,
where it remains attached to, and in communication with, the urethra: the
 
I
I
 
A.D.
4
 
I
 
1
 
I
 
     
 
FIG. 8.—A, B, C, D, a series of the. transverse sections through the
“lower subdivision” of the prostate, passing in that order from
below upwards. ‘
 
A.D., anterior ducts; Pr.S., prostatic sinus.
 
process of separation begins at the upper end. Ducts developed in this
manner possess a lumen from the outset.
 
With reference to the development of the prostatic ducts, Pallin observes
“so betrachte ich es als im hochsten Grade Wahrscheinlich, obschon nicht
ganzlich bewiesen, dass auch diese hinteren und demnach alle menschlichen
Prostatadriisen durch Abschniirung \'OIl longitudinalen Falten an der
Urethralwand angelegt werden ” (p. 142, Archie fitr Anatomie, 1901).
 
As regards the ducts which pass up and do not branch, Pallin’s statement
of their mode of origin is probably correct. The inferior horizontal ducts
(figs. 2 and 3, I.H.D.), which Pallin does not seem to have observed, and the
320 Mr Evelyn John Evatt
 
large ducts of the third lobe, cannot have been separated as longitudinal
folds.
 
I have not been able to satisfy myself that any of the prostatic ducts
grow out as“ solid buds.” On the contrary, I am inclined to believe that even
at the distal end of a given duct the presence of a lumen can be postulated
from the radial disposition of the cells lining the duct.
 
The Miillerian ducts coalesce for a short distance before entering the
posterior wall of the urethra upon the summit of the crista, between the
Wolflian ducts ; they then extend backwards as a bicornuate structure. The
left cornu as compared with the right is enormously developed and flattened
from side to side; it extends above and below the right, which is small and
flattened from above downwards (fig. 2, M.D.). At three and a half months
the Miillerian ducts enter the urethra at right angles to its long axis; at
birth it is seen to enter obliquely from above downwards and forwards.
 
The Wolffian ducts are also seen to enter the urethra at right angles to
its long axis and in the same horizontal plane with the Miillerian ducts.
 
The vesiculae seminales are observed growing out from the Wolflian
ducts as small, sac—shaped diverticula; at three and a half months they lie
in the genital cord outside the prostate (figs. 1, 2, '3, 4, and 5). It is only
with the further development of the latter that they come to lie in it.
 
The stroma of the prostate consists of white fibrous tissue and smooth
muscle; the latter is disposed in the periphery of the gland, but a few of
the fibres penetrate into the core of the gland. These muscle fibres can be
readily recognised at three and a half months. The stroma of the prostate
is derived from the mesenchyme of the urogenital sinus ; there appears to be
no morphological continuity between the stroma of the prostate and the
mesenchyme of the genital cord.
 
The prostatic capsule is derived entirely from the pelvic fascia, with
which it corresponds in structure. At birth this capsule is so sharply
marked off from the contained prostate that one could almost imagine the
prostateito move freely within it.
 
Lying deep to the anterior segment of the capsule, that is, within the
capsule, is a lamella of striated muscular tissue, “the musculus prostaticus.”
Its fibres pass transversely, and, in adaptation to the anterior surface of the
prostate, it is spoon-shaped; laterally, it gains attachment to the deep
surface of the capsule and blends with the stroma of the prostate; when
traced below, the muscle is seen to be continuous with the compressor
urethrae; superiorly, it terminates a little below the neck of the bladder.
This muscle is well marked at birth and is always present in the adult.
On mesial section it appears biconvex in outline; the thickest part of the
muscle (one—quarter inch in the adult) lies below the plane of the utriculus.
A Contribution to the Development of the Prostate in Man
 
BIBLIOGRAPHY.
 
BRYCE, Quaz'n’s Elements of Anatomy, vol. i. “ Embryology,” 1908.
 
DIXON, ’l'e:1:t-Book of Anatomy, edited by Cunningham, 1902.
 
KEITH, Human Embryology and Morpholngy, 1904.
 
GUSTAF PALLIN, Archiv fair Anatomie, 1901, “ Anatomie und Embryologie der
Prostata und der Samenblasen.” In the Archiv a very complete literature on the
development of the prostate may be found. ‘
 
STOHR, Text-Book of Histology, translated by Dr Alfred Schaper, p. 346.
 
J. W. THOMSON W'ALKEB, Jour. of Anat. and Phys., vol. xl., April 1906,
“On the Surgical Anatomy of the Prostate.”
 
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[[Category:Prostate]][[Category:Male]]
[[Category:Historic Embryology]][[Category:1900's]]

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