860 



TEE GENERATIVE APPARATUS. 



STRUCTURE. The vas deferens is formed, internally, by a very fine 

 mucous membrane covered with cylindrical epithelium, and to this is added, 

 externally, a contractile and a fibrous tunic. The contractile layer is formed 

 of three planes of unstriped fibres : the deep and superficial planes have 

 longitudinal, and the middle circular fibres. It is, proportionately, very 

 thick at the dilated portion of the duct, and it is to its great density that 

 the vas deferens owes its consistence as a hard, rigid cord. The mucous 

 membrane of the pelvic dilatation has tubular and acinous glands. 



2. The Vesiculce Seminales and Ejaculatory Ducts. (Fig. 326.) 



The vesiculce seminales are 

 Fig. 402. 



SUPERIOR VIEW OF THE PELVIC POR- 

 TION OF THE VASA DEFERENTIA, 

 VESICULCE SEMINALES, PROSTATE 

 GLAND, COWPER'S GLANDS, AND THE 

 INTRAPELVIC PORTION OF THE 

 URETHRA. 



1, Left vas deferens; 1', Its pelvic 

 dilatation; 2, 2, The same on the 

 right side ; 3, 4, Vesiculae seminales ; 

 5, The third vesicula; 6, Serous 

 layer uniting the vasa deferentia ; 

 7, That comprised between the two 

 vesiculae ; 8, Prostate gland ; 9, 

 lUadder seen through the serous 

 fold of the vasa deferentia ; 10, 

 Membranous or intrapelvic portion 

 of the urethral canal, covered by 

 Wilson's muscle; 11, 11, Cowper's 

 glands enveloped by that muscle ; 



12, 12, Ischio-cavernosus muscle; 



13, Accelerator urinae muscle. 



two oval pouches whose volume varies with 

 their contents, and which are placed in the 

 pelvic cavity, above the bladder and the vas 

 deferens. Each vesicula has a middle portion 

 and two extremities. The middle portion is 

 enveloped by a loose abundant cellular 

 tissue, and is in relation with the rectum 

 above, and below with the bladder and vas 

 deferens. 



The anterior extremity is the largest, 

 and forms a rounded cul-de-sac, covered in 

 almost the same manner as the bladder by 

 the peritoneum, which at this point fur- 

 nishes a very small triangular fraenum (the 

 recto-vesical fold) that unites the two vesi- 

 culee. The posterior extremity tapers to a 

 narrow neck, which passes beneath the pros- 

 tate gland, and joins at a very acute angle 

 the terminal extremity of the vas deferens, 

 to constitute the ejaculatory duct. 



.The walls of this pouch are composed 

 of three membranes : an internal mucous, a 

 middle muscular, and an external fibrous. 

 The mucous layer is continuous with that 

 of the ejaculatory ducts, and is very thin, 

 delicate, and follicular. It shows numerous 

 folds, which disappear with distention of the 

 duct. The middle layer evidently belongs 

 to the class of muscular membranes ; its 

 identity with that of the bladder is complete. 

 At the bottom of the cul-de-sac it gives off 

 several fasciculi, which radiate on the ex- 

 ternal surface of the peritoneum. (In addi- 

 tion to these, the vesiculse and vasa defe- 

 rentia have a muscular covering whose fibres 

 are arranged in a longitudinal and trans- 

 verse direction, the latter being the most 

 superficial. This muscular layer being con- 

 tinuous over the vesiculse seminales and vas 

 deferens, when it contracts, will compress 

 and shorten these ; consequently, it has been 

 named the compressor vesiculce ct ductus 



