224 



THE UROGENITAL SYSTEM 



generation is completed, the caudal ends of the testis lie at the boundary 

 line between the abdomen and pelvis, whereas the ovaries are located in 

 the pelvis itself, a position which they retain. Owing to the rotation of 

 the ovary about its middle point as an axis, it takes up a transverse position. 

 It also rotates nearly 180 about the Mullerian duct as an axis, and thus 

 comes to lie caudal to the uterine tube. 



The testis normally leaves the abdominal cavity and descends into 

 the scrotum. As described above, there is early developed between the 

 testis and the integument of the scrotum a fibrous cord, the gubernaculum 

 testis. Owing to changes in the position of the ventral abdominal wall and 

 umbilical arteries, changes connected with the return of the intestinal coils 

 into the coelom, there are formed in each side of the abdominal wall sac- 

 like pockets, the anlages of the vaginal sacs. Close to each saccus (processus) 

 vaginalis lies the caudal end of a testis, while extending into the scrotum out- 

 side the peritoneum is the gubernaculum testis. The saccus vaginalis later 





CLC 



did 



FIG. 234. The descent of the testis; a.c., Abdominal cavity; d.d., ductus deferens; g.t., 

 gubernaculum testis; s., scrotum; s.v., saccus vaginalis; t.v., tunica vaginalis; x., obliterated 

 vaginal sac. 



invaginates into the scrotum over the pubic bone. Due -to the actual and 

 relative shortening of the gubernaculum testis the descent of the testis 

 into the vaginal sac begins during the seventh month of fetal life, and, 

 by the end of the eighth month, or at least before birth, the testis is usually 

 located in the scrotum (Fig. 234). It must be remembered that the testis 

 and gubernaculum are covered by the peritoneum before the descent be- 

 gins, consequently the testis follows the gubernaculum along the inguinal 

 canal dorsal to the peritoneum, and, when it reaches the scrotum, is invag- 

 inated into the saccus vaginalis, but does not lie in the ccelomic extension. 

 The gubernaculum of a newborn is but one-fourth its length at the begin- 

 ning of the descensus. After birth it atrophies almost completely. 



Shortly after birth the narrow canal, connecting the saccus vaginalis 

 with the abdominal cavity, becomes solid and its epithelium is resorbed. 

 The vaginal sac, now isolated, becomes the tunica vaginalis of the testis. 

 Its visceral layer is closely applied to the testis and its parietal layer forms 

 the lining of the scrotal sac. The ductus deferens and the spermatic 

 vessels and nerves are of course carried down into the scrotum with the 

 testis and epididymis. They are surrounded by connective tissue, and, 



