96 



Anatomy of the Rabbit. 



with the coelomic cavity (Fig. 51 B). Their ciliated internal 

 openings, termed nephrostomes, are not developed in specialized 

 kidneys, but may be seen, even in the adult condition, in some 

 lampreys, where they communicate with that portion of the body 

 cavity enclosing the heart. 



In the rabbit, as in all mammals, the male gonad or testis (Fig. 55) , 



in which the male germ cells, 

 spermatozoa, are matured, 

 is connected with the peri- 

 pheral duct system (Fig. 52) 

 by means of the epididymis 

 and the ductus deferens, 

 parts of the mesonephric 

 connections of the embryo. 

 While the ductus deferens is a 

 single tube, the epididymis 

 THE consists of an ag- 

 TESTIS gregation of small 

 AND tubules, lying chiefly 

 toward the anterior 

 end of the testis, 

 but with the tubules not 

 individually discernible. The 

 testis is formed in the embryo 

 in all vertebrates in associa- 

 tion with the dorsal abdo- 

 minal wall, but in many 

 mammals moves backward to 

 a scrotal position, either 

 periodically or permanently 

 in the course of development. 

 This change, known as the descent of the testis, is brought about 

 through the agency of a muscular cord, the gubernaculum, the 

 connections of which in the rabbit, are retained in the adult condi- 

 tion. The migration of the organ determines a number of peculiar- 

 ities in the relations of its bloodvessels and peritoneal Connections. 

 The female gonad or ovary (Fig. 53) lies on the dorsal wall of the 

 abdominal cavity, thus retaining to a large extent the primitive 



ITS 

 DUCT. 



Fig. S3. The female urinogenital system: a, 

 aorta: as, internal spermatic artery; au, umbilical 

 artery; c, clitoris; gp, perineal gl%nd; gr, rectal 

 gland; h, hydatid of uterine tube; hr, middle 

 haemorrhoidal artery; i, inferior caval vein; lo, 

 ovarian liga:ment; It, round ligament; lu, umbilical 

 ligament; ms, mesosalpinx; mt, mesometrium; 

 o, ovary; ot, ostium tubse; r, rectum; rp, peritoneal 

 recess (rudimentary vaginal process) ; cu, uterine 

 tube; u, ureter; ut, uterus; vg, vagina; vs, vesti- 

 bulum; vu, urinary bladder. 



