THE GENITAL GLANDS — DESCENT OF TESTIS 



231 



pelvis while the ovaries are located in the pelvis itself, a position which they re- 

 tain. 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 Muellerian 

 duct as an axis and thus comes to He caudal to the uterine tube. 



The testis normally leaves the abdominal cavity, descending into the scro- 

 tum. 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 ccelom, there 

 are formed in each side of the abdominal wall sac-like pockets, the anlages of the 

 vaginal sacs. Close to each saccus vaginalis lies the caudal end of a testis, while 

 extending into the scrotum beneath the peritoneum is the gubernaculum testis. 

 The saccus vaginalis later invaginates into the scrotum over the pubic bone, carry- 

 ing with it also representatives of the 

 muscular layers of the abdominal wall. 

 Whether due to the active shortening 

 or to the unequal growth of the guber- 

 naculum testis, the descent of the testis 

 into the vaginal sac begins during the 

 seventh month of fetal life and by the 

 eighth month or at least before birth 

 the testis is usually located in the scro- 

 tum (Fig. 227). It must be remem- 

 bered that the testis and gubernaculum are covered by the peritoneum before 

 the descent begins, consequently the testis follows the gubernaculum along the 

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

 invaginated into the saccus vaginalis. The gubernaculum is said to degenerate 

 during the descent of the testis or immediately after. Abnormally, the testis 

 may remain in the abdomen, a condition known as cryptorchism (concealed 

 testis) and associated with sterility in man. In some mammals (bat and 

 elephant) it is the normal condition. 



Shortly after birth the inguinal canal connecting the saccus vaginalis with 

 the abdominal cavity becomes solid and its epithelium is resorbed. The now 

 isolated vaginal sac 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 spermatic vessels are of course carried down into 

 the scrotum with the testis and epididymis. They are surrounded by connective 



Fig. 227. — Descent of the testis (Cunning- 

 ham), ac, abdominal cavity; pv, processus 

 vaginalis; t, testis; 5, scrotum; tv, tunica vagin- 

 alis; x, rudiment of processus vaginalis. 



