THORAX AND ABDOMEN OF THE HORSE 



181 



with that of the same organ in the male, but there are no deferent 

 ducts, seminal vesicles, or prostate associated with its neck. As in the 

 male, the peritoneum is rejected from its mid-ventral aud lateral 

 aspects to the pelvic wall in the form of three triangular membranous 

 sheets. In the female the peritoneum is reflected from the dorsal wall 

 of the bladder on to the vagina, close to its junction with the uterus. 

 In other words, the uterus and a very short length of the vagina occupy 

 the homologue of the urogenital fold (now the broad ligaments) of the 

 male. The peritoneal pouch between the uterus and the bladder is 

 designated the vesico-uterine excavation (excavatio vesicouterina). 



Mesorectum. 



Rectum. 



Recto-uterine excavation 



Broad ligament. 



Vesico-uterine excavation. 



- Ureter. 



Uterus. 



Lateral vmiliilical fold. 



Urinary bladder. 



Middle umbilical fold. 



Fig. 79. — Diagram to illustrate the arrangement of the peritoneum in the female 

 pelvis. Transverse section. The red line represents the peritoneum. 



The vagina occupies a position dorsal to the bladder and urethra 

 and ventral to the rectum. 



The broad ligaments are continued for a short distance into the 

 pelvic cavity. Converging and gradually narrowing, they cease to 

 exist as such, and the peritoneum is reflected from the vagina, close to 

 its junction with the uterus, on to the rectum. The broad ligaments in 

 this manner circumscribe a peritoneal pouch, the recto-uterine excava- 

 tion (excavatio rectouterina), which intervenes between the uterus and 

 a small portion of the vagina on the one hand, and the rectum and 

 termination of the small colon on the other. The terminal portion of 

 the intestine is suspended in the excavation by a short mesentery. 



The pelvic cavity (cavum pelvis). — Since the young is born by 

 passing through the pelvis, the dimensions of tiie cavity in the female 

 are of obstetric interest. And seeing that the inlet to the cavity is 



