The; Urinoge;nital System. 131 



(c) The deferent ducts lie between the seminal vesicle and the 

 dorsal wall of the bladder. They terminate in the ventral 

 wall of the seminal vesicle. 



(d) The prostate (prostata), a white or yellowish mass of 

 glandular tissue, lies in the posterior portion of the dorsal 

 wall of the seminal vesicle. Its ducts, three or four in 

 number on either side, open into the urethra. Accessory 

 paraprostatic glands (gl. paraprostaticae), minute finger-like 

 projections of the urethal wall, lie on either side of the base 

 of the seminal vesicle. 



(e) The bulbourethral gland (gl. bulbourethralis) ; situated on 

 the dorsal wall of the urethra behind the prostate. 



3. The internal surface of the dorsal wall of the urethra may be 

 exposed by a longitudinal incision extending into the bladder. The 

 crescentic aperture of the seminal vesicle lies immediately in front of 

 an oval elevation, the coUiculus seminalis, on either side of which some 

 of the minute apertures of the prostate may be made out. 



C. The Female Genital Organs. 



1. The organs may be traced from the abdominal cavity backward, 

 as follows : 



(a) The ovary (ovarium) is a small — in young animals minute — 

 elongated structure of greyish or yellowish coloration lying 

 on the dorsal body-wall some distance behind the kidney. It 

 is readily distinguished by the circular translucent dots 

 representing the larger vesicular ovarian follicles. In some 

 cases the darker radiate impressions (corpora lutea) left by 

 extruded eggs are discernible. 



(b) The mesovarium, a short fold of peritoneum suspending the 

 ovary from the body- wall. 



(c) The internal spermatic artery (a. spermatica interna) arises 

 from the abdominal aorta, immediately behind the origin 

 of the inferior mesenteric artery, and crosses the body-wall 

 transversely to the ovary. 



(d) The spermatic vein (v. spermatica) leaves the medial side of 

 the ovary, and crossing the body-wall enters the inferior 

 caval vein. 



(e) The uterine tube (tuba uterina), the first portion of the ovi- 

 duct, distinguishable by its narrow calibre, opens into the 

 abdominal cavity through a broad funnel-like expansion, the 

 ostium abdominale tubae uterinae. The margin bears a large 

 number of short folds and processes, the fimbriae tubae, 

 w^hich tend to enclose the margin of the ovary. 



(f) The mesosalpinx is the peritoneum supporting the uterine 

 tube. It is continuous with the mesovarium. 



(g) The uterus, the second portion of the oviduct; distinguished 



