414 DIGESTIVE SYSTEM OF THE HORSE 
forming the visceral peritoneum for the first part of that tube.' Laterally it is 
reflected in a similar fashion. If the rectum be raised, it will be seen that the 
peritoneum passes from its ventral surface and forms a transverse fold which lies 
on the dorsal surface of the bladder (Fig. 870). This is the genital fold (Plica 
genitalis). Its concave free part passes on either side into the inguinal canal. 
The ventral layer of this fold is reflected on to the dorsal surface of the bladder. 
Thus there is formed a pouch between the rectum and bladder—the recto-vesical 
pouch (Excavatio recto-vesicalis), which is partially subdivided by the genital 
fold into recto-genital and vesico-genital cavities. The fold contains the ductus 
deferentes, part of the vesiculee seminales, and the uterus masculinus (a foetal 
remnant). If the bladder is now raised, it is seen that the peritoneum passes 
Left extremity 
(Esophagus 
Duodenuwm 
Antrum pyloricum 
Fig. 354.—Stomacna or Horse; ParteraL SURFACE. 
The organ was fixed in situ when well filled. The lesser curvature has been opened up slightly and the peritoneum, 
etc., in this vicinity removed. The larger branches of the anterior gastric artery and vein are visible. | 
from its ventral surface on to the pelvie floor, forming centrally the median um- 
bilical fold or middle ligament of the bladder (Plica umbilicalis media). It also 
passes from each side of the bladder to the lateral pelvic wall and forms thus 
the lateral umbilical fold or ligament of the bladder (Plica umbilicalis lateralis); 
this contains in its edge the so-called round ligament of the bladder (Ligamentum 
teres vesice)—the partially occluded umbilical artery, which is a large vessel 
in the fcetus. 
In the female the arrangement is modified by the presence of the uterus; 
1The point at which the reflection takes place is quite variable, and apparently depends 
chiefly on the amount of feces in the rectum. When the bowel is very full the reflection may be 
little behind the promontory; when it is empty, the reflection may be at the posterior end of the 
sacrum. 
In the foetus and new-born foal these three folds extend to the umbilicus in conformity with 
the abdominal position of the bladder. When the latter becomes a pelvic organ, the lateral folds | 
conform to the change and end at the vertex of the bladder. The median fold may still be trace- 
able to the umbilicus. 
