PROCESSUS 

 VAGINALIS 



PERITONEAL 

 CAVITr 



f^ OBLITERATED 

 INGUINAL 

 CANAL 

 TESTIS 

 GUBERNACULUM 



SEROUS CAVITY 

 . (INGUINAL BURSA) 



WALL TISSUE 

 (EE FIG S 



VAS DEFERENS 



EPI 01 DYMIS 

 TESTIS 



TESTICULAR 

 LIGAMENT 



PATENT INGUINAL CANAL 



SCROTAL BULGE 



Fig. 4. Diagrammatic drawings portraying the relationship of the testis to the processus 

 vaginalis (peritoneal evagination) and the scrotum. The testis is at all times retroperi- 

 toneal, i.e., outside the peritoneal cavity and membrane. (A) Earlier stage of testicular 

 descent at the time the testis is moving downward into the scrotum. (B) Position of 

 the testis at the end of its scrotal journey in a form possessing permanent descent of the 

 testis, e.g., man, dog, etc. (C) Testis-peritoneal relationship in a form which does not 

 have a permanent descent of the testis — the testis is withdrawn into the peritoneal cavity 

 at the termination of each breeding season. Shortly before the onset of the breeding 

 period or "rut," the testis once again descends into the scrotum, e.g., ground hog. (D) 

 Position of testis in relation to body wall and peritoneum in the mole, shrew, and hedge- 

 hog in which there is no true scrotum. The testis bulges outward, pushing the body wall 

 before it during the breeding season. As the testis shrinks following the season of rut, 

 the bulge in the body wall recedes. True also of bat, Myotis. 



STOMA CH 

 PECTORAL FIN 



MEMAL PUBIC PROCESS 



TAIL MUSCLE 



LATERAL LINE 



ANUS 



UROGENITAL OPENING / / \ "TAIL COELOM 



ABDOMINAL COELOM / TESTIS 



DUCTUS DEFERENS 



CONTAINING TESTIS 



Fig. 5. Opened peritoneal cavity of a common flounder, Limanda ferruginea, showing 

 the position occupied by the testes. Each testis is situated partly in a separate compart- 

 ment on either side of the hemal processes of the tail vertebrae. 



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