Clinical Anatomy of the European Hamster 
The main tributaries from the caudomesocolic 
viscera emptying into the vena cava (in cranial di- 
rection) include the testicular and ovarian, respec- 
tively, in males and females; the renal veins; and 
the portal shunt-hepatic vein system. Since the 
hepatic veins (vv. hepaticae) are so small and (Fig. 
5-35) vary greatly from animal to animal, the 
exact number draining the different lobes of the 
liver cannot be exactly determined. For example, 
tributaries from the caudate lobe are not demon- 
strable and probably empty into the caudal vena 
cava during its transit through the liver. Other col- 
lecting branches enter the ventral side of the vena 
cava just caudal to the foramen venae cavae. 
Because the walls of the larger vessels passing 
through the liver are embedded in liver connective 
tissue, they do not easily collapse, so that hemor- 
rhage in the liver is often diagnostically critical. 
5.6.5.3 Portal Circulation 
The hepatic portal system includes those veins 
draining the gastrointestinal tract caudal to the 
diaphragm, whose blood is transported to the liver 
by the portal vein {v. porta) for circulation through 
the liver sinusoids before returning to the systemic 
circulation via the hepatic veins and caudal vena 
cava (Fig. 5-34). The portal vein is formed chiefly 
by the gastroduodenal vein {v. gastroduodenalis), 
splenic vein {u. lienalis) and cranial mesenteric vein 
{v. mesenterica cranialis). The cranial mesenteric 
vein is formed by branches from the jejunum {vv. 
jejunales) and ileum {vv. ilei), and by the ileocolic 
{v. ileocolica), right colic {v. colica dextra) and mid- 
dle colic {v. colica media) veins, from the ascending 
and transverse colons. The caudal mesenteric vein 
{v. mesenterica caudalis), arising from the cranial 
rectal {v. rectalis cranialis) and left colic veins {v. 
colica sinistra), and draining the descending colon 
and rectum, also discharges into the cranial mesen- 
teric vein. All of these vessels run through the mes- 
entery and, at the level of the eleventh thoracic 
vertebra, join to form the portal vein, which runs 
to the liver, dorsal to the common bile duct and 
dextrodorsal to the hepatic artery within the hepa- 
toduodenal ligament. At this level, the portal vein 
gives off two branches corresponding to the right 
and left lobes of the liver. 
5.7 LYMPHATIC SYSTEM OF THE 
ABDOMEN AND PELVIS 
5.7.1 Lymph Nodes of the 
Gastrointestinal Tract 
The lymph nodes of the abdominal viscera are 
organized into two major lymph centers, the coeliac 
{lymphocentrum coeliacum) and the cranial mes- 
enteric {lymphocentrum mesentericum craniale), 
which empty into the cisterna chyli. The cisterna 
chyli represents a dilated portion of lymphatic trunk 
situated between the crura of the diaphragm at the 
level of the last thoracic to the second lumbar ver- 
tebrae. It receives the coeliac {truncus coeliacus), 
lumbar {truncus lumbalis) and intestinal {truncus 
intestinalis) trunks, and continues intrathoracically 
as the thoracic duct. 
5.7.1.1 Coeliac Lymph Center 
The following nodes all drain through the coeliac 
trunk. The gastric lymph nodes {Inn. gastrici), 3 to 
5 in number, are situated along the pylorus and the 
proximal duodenum, as well as within the gastro- 
splenic ligament. Occasionally one or two may also 
be found within the greater omentum. They drain 
the fore- and glandular stomachs, duodenum, 
spleen and greater omentum. 
The hepatic lymph nodes {Inn. hepatici) lie dor- 
sal to the right lobe of the pancreas, between the 
pancreas and the portal vein (Fig. 3-12). The ac- 
cessory hepatic lymph nodes {Inn. hepatici acces- 
sorii) are situated within the hepatoduodenal liga- 
ment (Fig. 3-12). They too drain the liver. 
The pancreaticoduodenal lymph nodes {Inn. 
pancreaticoduodenales), 4 to 7 in number, lie within 
the gastroduodenal ligament and the greater omen- 
tum immediately ventral to the right lobe of the 
pancreas. (They are sometimes difficult to distin- 
guish from the pancreatic tissue.) They drain parts 
of stomach and liver, the pancreas and duodenum. 
5.7.1.2 Cranial Mesenteric Lymph 
Center 
The following nodes drain through the intestinal 
trunk: the cranial mesenteric lymph nodes {Inn. 
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