COMPARATIVE ANATOMY OF THE CIRCULATORY SYSTEM 223 



2. The hepatic portal system and the ventral abdominal vein. — In the 



median ventral line of the body wall, posterior to the liver, inclosed in the falci- 

 form ligament is situated the ventral abdominal vein. It is homologous with 

 the lateral abdominal veins of the elasmobranchs. It receives parietal branches 

 from the body wall. At the level of the posterior end of the liver it leaves the 

 body wall and passes into the liver where it is situated on the dorsal surface. 

 After a short course it joins the hepatic portal vein at the place of attachment 

 of the hepatoduodenal ligament. 



The hepatic portal vein is the vein which collects the blood from the digestive 

 tract. It is formed by the union of branches from the intestine, pancreas, spleen, 

 and stomach. Stretch out the dorsal mesentery of the small intestine. In 

 this mesentery about halfway between the body wall and the intestine runs a 

 conspicuous vein, the mesenteric vein. Trace it posteriorly and note its begin- 

 ning in the wall of the large intestine. As it passes forward in the mesentery it 

 receives numerous intestinal veins from the small intestine. It then passes into 

 the substance of the pancreas receiving small pancreatic veins from that organ. 

 At the level of the pancreas the large gastrosplenic vein also joins the mesenteric 

 from the left. On following the gastrosplenic to the spleen it will be found to 

 be formed of splenic branches from the spleen and gastric veins from the stomach. 

 The union of the mesenteric, gastrosplenic, and pancreatic veins produces a 

 large vessel, the hepatic portal vein, which lies along the center of the dorsal 

 face of the liver. It also receives the ventral abdominal vein as already noted. 

 Follow it along the surface of the liver. It branches into the liver substance 

 and in its course also receives additional gastric veins from the stomach and also 

 veins from the ventral body wall which pass into the liver by way of the falci- 

 form ligament. (These have probably been destroyed in the study of the diges- 

 tive tract.) The hepatic portal vein subdivides in the substance of the liver and 

 eventually passes into capillaries. 



Draw the hepatic portal system. 



3. The renal portal system. — Trace the ventral abdominal vein posteriorly. 

 It soon receives some vesical veins from the bladder. Shortly anterior to the 

 hind limbs the abdominal vein is seen to be formed by the union of the two 

 pelvic veins which run along the inner surface of the lateral body wall just in 

 front of the pelvic girdle. Follow one of the pelvic veins. It is joined by the 

 femoral vein from the hind limb. The vein formed by this union is the renal 

 portal vein. It passes at once to the dorsal surface of the adjacent kidney. In 

 male specimens the kidney is a brownish organ of considerable size situated at 

 the side of the intestine. In female specimens the kidney is much smaller and 

 more slender, and is situated at the common point of attachment of the mesova- 

 rium and mesotubarium. It will be located by laying the ovary to one side and 

 the oviduct to the other side. At the posterior end of the paraperitoneal cavity 

 the kidney in the female lies between the intestine and the oviduct. Having 



