1294 



THE UKO-GENITAL SYSTEM 



shape. The seminal vesicles are more intimately related to the wall of the bladder 

 than to that of the rectum. Their superior ends are, as we have seen, separated 

 from the rectum by a portion of the recto-vesical pouch of peritoneum, and 

 lower down the septum of fascia which intervenes between the vesiculse seminales 

 and the rectum is denser than that which separates them from the bladder. 



Each vesicula seminalis is in reality a tube bent in a tortuous manner on itself, 

 and if the dense connective tissue which envelops it is taken away, the length of 

 the tube when untwisted may be found to be as much as five inches. The tube is 

 closed above, and a variable number of short tortuous branches come off it at 

 different levels. The blind end of the tube usually lies at the superior and lateral 

 extremity of the seminal vesicle, but in some cases the tubular vesicle is so bent 

 upon itself that the blind terminal part lies against the side of the issuing duct 

 The development of the vesiculse seminales shows that they are to be regardec 

 as diverticula of the ductus deferentes, from which they originally arise as smal 

 pouches. 



The dense tissue in which the seminal vesicles are embedded contains much unstriped muscle 

 tissue, which sweeps round in the side wall of the recto-vesical pouch. Inferiorly this tissue 

 is attached to the capsule of the prostate. The large veins coming from the prostatic anc 

 vesical plexuses are closely related to the seminal vesicles. 



Superior surface 

 of bladder 



. um- Seminr 

 vesicl 



Lateral aspect 

 of prostate 



Urethra 



Lateral 

 aspect of 

 prostate 



Median 

 umbilict 

 ligamenl 

 (urachus 



Infero-lateral 

 area of bladder 



Urethra 



FIG. 1013. THE URINARY BLADDER; PROSTATE, AND SEMINAL VESICLE VIEWED FROM THE SIDE. 

 Drawn from specimens hardened in situ. 



In A the bladder contained but a small amount of fluid ; in B the quantity was somewhat greater. 



Structure of the Ductus Deferens and of the Vesicula Seminalis. 



Except near its termination, where it is dilated to form the ampulla, the ductus deferens 

 is a thick-walled tube with relatively a very small lumen. The hard cord-like sensation 

 which the ductus deferens conveys to the touch is due to the thickness and toughness oi 

 its wall, which is composed of three layers an outer fibrous tunica adventitia, an inter- 

 mediate tunica muscularis, and an inner tunica mucosa. The thickness of the wall is 

 due to the great development of the middle or muscular coat, which is composed of an 

 intermediate layer of circularly and an inner and outer layer of longitudinally directed 

 unstriped muscular fibres. Of these layers the middle one is by far the thickest, and 

 forms the chief part of the thickness of the wall of the ductus deferens. The mucous 

 membrane of the duct exhibits a number of slight longitudinal folds and possesses a ciliated 

 epithelium. The ampulla, or terminal part, possesses a much thinner wall, and, as the 

 surface of its mucous membrane has a number of ridges separating depressed areas, the 

 lining of this part of the tube presents a pitted or honeycombed appearance. The wall oi 

 the vesicula seminalis resembles that of the ampulla in being thin, and in having a mucous 

 lining with uneven honeycomb-like ridges and depressions. In it the same coats are tc 

 be recognised as in the ductus deferens, but the muscular layer is much thinner, and the 

 strata composing it less regularly arranged. 



