IOO 



Anatomy of the Rabbit. 



digestive tube, and is therefore considered as divided into corres- 

 ponding parts. In many cases the relations of these are greatly 

 complicated by secondary adhesions. In the rabbit the mesoduo- 

 denum, mesentery, and descending mesocolon will be recog- 

 nized as parts in which a more typical arrangement is retained. 

 Moreover, in the anterior portion of the abdominal cavity the 



peritoneum is concerned not only 

 with the investment of two large 

 visceral structures, the stomach and 

 the liver, but also with the formation 

 of a lining for the posterior surface 

 of the diaphragm. Thus the general 

 condition is less simple than in the 

 small and large intestines. The 

 peritoneum, passing from the dorsal 

 wall, successively invests the spleen, 

 the stomach, and the liver, and is 

 reflected from the last-named struc- 

 ture to the diaphragm and the ventral 

 body- wall through the coronary, 

 triangular, and falciform liga- 

 ments. Its gastric portion is differ- 

 entiated into the mesogastrium 

 (phrenicosplenic and gastrolienal 

 ligaments), the greater omentum, 

 and the lesser omentum. Similarly, 

 in the posterior part of the body the 

 peritoneum passes from the rectum 

 to the urinary bladder, enclosing also 

 It is then reflected to the ventral bodv- 



Fig. 55. Diagram showing the rela- 

 tion of the testis to its investments: 

 a.i.. inguinal ring; c.e., caput epididy- 

 midis; cr., cremaster muscle; dd, ductus 

 deferens; g, gubernaculum; mes, mes- 

 orchium; ptv, and vtv, parietal and 

 visceral layers of the tunica vaginalis 

 propria; pv, cavity of the vaginal pro- 

 cess; s, integument of the scrotum; 

 sv, spermatic vessels; t, testis. 



in the female the vagina. 



wall as the middle umbilical fold. 



In the male, as indicated in the accompanying diagram (Fig. 55), 

 the peritoneal relations of the testis are greatly modified by the 

 migration of the organ from an abdominal to a scrotal position. 

 The entire sac lodging the testis is an evaginated portion of the 

 abdominal wall, and since in the rabbit the cavity is widely open 

 throughout life to the abdominal cavity the lining membrane — that 

 designated as the parietal layer of the tunica vaginalis propria— 



