Abdomen and Pelvis 
vesicogenitalis). In males, it covers a much less 
prominent vesicogenital pouch and reflects directly 
over the bladder. After investing the cranial surface 
of the bladder, the peritoneum moves cranially 
along the ventral abdominal wall. 
5.6.2 Caudomesocolic Viscera and 
Relations 
The convoluted intestines of the European ham- 
ster are subdivided into the duodenum, jejunum, 
ileum, caecum, colon and rectum (Figs. 5-36, 5- 
37). The total length of the gut averages 1425 mm 
in males (n = 10, s.d.=250 mm) and 1100 mm in 
females (n = 10, s.d.=250 mm). The total length of 
the gut is thus 4 to 5 times the length of the body. 
The weight of the distended intestines is 28.7 g ± 
4.0 g in males and 22.9 g ±. 4.0 g in females (Tables 
3, 6). 
5.6.2.1 Structure of the Small 
Intestine 
The small intestine {intestinum tenue) extends 
from the pylorus to the iliocaecal junction {ostium 
lie ale). 
The intestinal wall is composed of serous, muscular, submucous and 
mucous layers (Fi^. 5-38) The serous layer is formed of visceral peri- 
toneum, which merges with the subserous stratum of areolar connective 
tissue. The muscular coat is thicker in the cranial than in the caudal 
part of the small intestine. It consists of a thin outer longitudinal and a 
thicker inner circular layer of nonstriated muscle fibres. The submu- 
cous layer consists of submucous glands and loose connective tissue 
with blood vessels, lymphatics and nerves. The mucous membrane is 
thick and highly vascular in the upper part of the small intestine but 
thinner and less vascular in the lower part. It is thrown into circularly 
or spirally arranged folds; the circular folds and the entire surface are 
composed of Hngerlike, filiform projections, the intestinal villi. Ex- 
tending into the mucosa from the surface between the intestinal villi are 
simple tubular intestinal glands {gll. intestinales). They reach almost 
to the muscular layer. In the duodenum are mucous tubuloalveolar 
duodenal glands {gli duodenales), the ducts of which extend through 
the muscular layer to proliferate in the submucous coat. 
5.6.2.2 Duodenum 
The duodenum of the European hamster is seg- 
mented into cranial (pars cranialis), descending 
(pars descendens) and ascending (pars ascendens) 
parts. This portion of the intestine is about 140 mm 
long and 3.5 mm wide, and it is from light yellow 
to whitish-red in color. After the first flexure (flex- 
ura duodeni cranialis) the duodenum runs ventral 
to the caudal process of the liver and ventromedial 
to the right kidney and continues in a caudomedial 
direction as the descending part. The descending 
part forms an arch convex towards the midline, 
turns around at a second flexure (Jlexura duodeni 
caudalis) in the pelvic region and continues crahio- 
medially as the ascending segment to the visceral 
surface of the stomach. The ascending part of the 
duodenum turns to the right and runs between the 
jejunal loops and the transverse colon, where it be- 
comes the jejunum. The ascending duodenum is 
connected to the descending colon, and the descend- 
ing duodenum is fixed to the ascending colon by the 
duodenocolic ligament (plica duodenocolica) ven- 
tral to the kidneys. 
5.6.2.3 Jejunum 
The transition of the duodenum into the jejunum 
is not visible superficially, nor is the transition of 
jejunum into the succeeding ileum. The sharply 
contorted loops of the jejunum are situated pre- 
dominantly in the dorsal region of the mesogas- 
trium, or mesentery attached to the greater curva- 
ture of the glandular stomach (Figs. 5-39, 5-40). 
Due to a long mesojejunum, the entire jejunum is 
easily tractable (Fig. 5-41). With a length of about 
350 mm and a width of approximately 4 mm, it is 
the longest segment of the intestine; the serous sur- 
face is grayish-red in color. The jejunal loops rest 
dorsally against the duodenum and the ascending 
colon, ventrally against the abdominal wall in the 
umbilical region, and caudally against the urinary 
bladder as well as the epididymal fat in males. 
Cranial to the base of the caecum, the jejunum 
merges into the ileum. 
In the jejunum the mucous membrane forms especially tall villi 
(Fig. 3-42). 
5.6.2.4 Ileum 
The length of the ileum is between 20 and 
25 mm, while the width may be up to 3 mm. The 
serous surface of the ileum is generally grayish- 
yellow green in color. The ileocaecal ligament 
(plica ileocaecalis) extends as a broad band between 
the ileum and caecum. Originating at the border 
between the jejunum and ileum, the ligament grad- 
ually narrows as it approaches the dorsal surface 
of the caecum. At the point of attachment, the ileum 
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