Paper - A contribution to the development of the prostate in man
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Evatt EJ. A contribution to the development of the prostate in man. (1909) Jour. of Anat. and Phys. 43: 314-321.
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A Contribution to the Development of the Prostate in Man
By Mr Evelyn John Evatt, University College, Cardiff.
- 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.
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.
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 (vesiculae 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 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 of 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. Transverse 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 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 of 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 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 process of separation begins at the upper end. Ducts developed in this manner possess a lumen from the outset.
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.
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 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.
BRYCE, Quain’s Elements of Anatomy, vol. i. “ Embryology,” 1908.
DIXON, Text-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 WALKER, Jour. of Anat. and Phys., vol. xl., April 1906, “On the Surgical Anatomy of the Prostate.”
Cite this page: Hill, M.A. (2020, January 25) Embryology Paper - A contribution to the development of the prostate in man. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_A_contribution_to_the_development_of_the_prostate_in_man
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