336 Veterinary Obstetrics 



testes and the Isitter, by further growth, form the head of the 

 epididymis. The upper, or anterior, end of the Wolffian duct is 

 modified to constitute the body and tail of the epididymis, while 

 the posterior portions form the vas deferens, seminal vesicle and 

 ejaculatory duct. 



Early in fetal life, the developing testicle shifts its location 

 from its primary lumbar position toward its final normal resting 

 place, in most animals in the scrotum. Formed in the per- 

 itoneum of the body wall in the sub-lumbar region, the gland is 

 outside or behind the parietal peritoneum and, as it .shifts its po- 

 sition and descends into the cavity of the abdomen toward the in- 

 ternal abdominal ring, it necessarily carries with it a peritoneal 

 covering and remains attached to its point of origin by a double 

 peritoneal fold, mesentery or mesorchon, between which its vessels 

 and nerves pass. 



In the formation of the Wolffian body, there arises, in con- 

 nection with it, the inguinal ligament, which passes from the 

 fundus of the scrotum through the inguinal ring up to the 

 Wolffian body. When this atrophies and disappears, the cord 

 persists and maintains a connection with the testicle, as the 

 gubernaculum testis, or with the ovary, as the round ligament. 

 The gubernaculum testis consists of connective tissue and un- 

 striped muscle fibers, surrounded by peritoneal coverings. Since 

 the testicle, the gubernaculum testis, and the vas deferens, origi- 

 nating from the Wolffian duct,- form outside of or behind the 

 peritoneum, as the organ descends each of the three structures 

 must drag with it a double peritoneal fold, so that finally there 

 appear three peritoneal folds, as shown in Figs. 56 and 57 : one for 

 the testicle and its artery, A ; one for the vas deferens, V, and a 

 third for the gubernaculum testis, G, G', and G", all of which 

 are continuous. 



As. the organ continues to descend toward the inguinal ring, 

 the peritoneum of the abdominal floor, which stretches across the 

 ring, evaginates through it as the processus vaginalis at P. in 

 Figs. 56 and 57, into which pouch the epididymis, E, descends, 

 followed later by the gland, T. The testis having formed on 

 the median side of the Wolffian duct, which later forms the 

 epididymis, the two structures maintain this original relation 

 throughout and, when the testicle comes to rest in the scrotum. 



