THE GENITAL ORGAXS 



129 



of every vertebrate, the testis is formed in association with the dorsal 



rs-.i abdominal wall, but in many 



m 



T 



mammals it moves backward 

 either periodically or perma- 

 nently in the course of de- 

 velopment, to a position in a 

 separate sac derived from the 

 posteroventral part of the 

 coelom, the scrotal sac. This 

 change in position, known as 

 the descent of the testis, has 

 been shown to be an adap- 

 tation for temperature regu- 

 lation in that organ. It is 

 controlled by a cord of muscle 

 and connective tissue, the 

 gubernaculum, which is re- 

 tained in the adult rabbit as 

 a fibrous band attaching the 

 testis to the end of the scrotal 

 sac. The migration of the 



Fig. 77. The female urinogenital system: 

 a, aorta; as, internal spermatic artery; au, 

 umbilical artery; c, clitoris; gp, inguinal gland; 

 gr rectal gland; h hydatid of uterine tube; hr orS:an determines a UUmbcr 

 middle hasmorrnoidal artery; i, inferior caval ° 



vein; lo. ovarian ligament; It, round ligament; 

 lu. umbilical ligament; ms, mesosalpinx; mt, 

 mesometrium; o, ovary; ot, ostium tubae; r, of itS blood-VCSScls and pcri- 

 rcctum; rp, peritoneal recess (rudimentary 



vaginal process); tu, uterine tube; u, ureter; tOUCal COUnCCtlOnS. 

 v.t. uterus; vg, vagina; vs, vestibulum; vu, 

 urinary bladder. 



of peculiarities in the relations 



The Ovary and Oviducts 



The female gonad or ovary (Fig. 77) lies on the dorsal wall of 

 the abdominal cavity, thus retaining to a large extent the primitive 

 position. It has, however, gubernacular connections corresponding 

 with those of the testis and these are plainly discernible in the adult 

 animal as the ovarian and round ligaments, of which the latter 

 is inserted into a small pocket of the abdominal wall simulating 

 the testis sac. 



Though inconspicuous in gross size as compared with the testis, 

 the ovary is concerned wdth the formation of cells of relatively large 

 dimensions, the female germ cells or ova (Fig. 1), which, however, are 



