212 LABORATORY MANUAL FOR VERTEBRATE ANATOMY 



consists of veins which collect the venous blood from the digestive tract and 

 spleen, and pour it into a network of capillaries in the liver. Locate the bile 

 duct. Lying in the hepatoduodenal ligament alongside the bile duct is a large 

 vein, the hepatic portal vein. Trace it posteriorly and identify the branches 

 which it receives from the digestive tract. 1 These branches differ slightly in the 

 three forms under consideration. 



Spiny dogfish: On tracing the hepatic portal vein posteriorly, it will be 

 found to receive first a very small branch, which may be called the duodenal 

 branch, which runs along the bile duct and collects from the duodenum and 

 anterior portion of the spiral valve. Posterior to this the hepatic portal vein is 

 seen to be formed by the union of three large branches. The left branch, the 

 gastric vein, passes at once to the stomach, where it is formed by the union of 

 the dorsal and ventral gastric veins, which branch on the dorsal and ventral sur- 

 faces of the stomach. The middle of the three main branches of the hepatic 

 portal is the lienomesenteric vein. It passes posteriorly dorsal to the duodenum 

 and is imbedded in the substance of the dorsal lobe of the pancreas, from which 

 it receives branches. At the posterior end of the pancreas the vein is seen to be 

 formed by the union of two branches: one, the posterior splenic vein, from the 

 spleen; and the other the posterior intestinal vein, which comes from the left 

 side of the small intestine. Note its numerous branches from the intestinal wall 

 along the lines of attachment of the turns of the spiral valve. The right branch 

 of the three that form the hepatic portal vein is the pancreatico-mesenteric. It 

 passes dorsal to the pylorus and is imbedded in the substance of the ventral lobe 

 of the pancreas. Here it receives the anterior splenic vein from the anterior 

 part of the spleen and several veins from the pancreas and duodenum. Its main 

 trunk, the anterior mesenteric vein, is situated along the right side of the intestine 

 from which it receives branches hi the same manner as the posterior intestinal 

 vein. 



Smooth dogfish: The branches are similar to those of the spiny species. 

 The hepatic portal first receives the very small duodenal branch from along the 

 bile duct and shortly beyond this point is formed by the union of three large veins : 

 the gastric vein on the left, the lienomesenteric in the middle, and the pancreatico- 

 mesenteric to the right. The gastric vein passes toward the stomach and receives 

 an anterior ventral gastric vein. It is situated in the mesentery between the two 

 limbs of the stomach and in its course receives branches from both limbs. The 

 lienomesenteric vein passes dorsal to the pylorus lying imbedded in the dorsal 

 lobe of the pancreas. At the anterior margin of this lobe of the pancreas it 

 receives the anterior dorsal gastric vein from the corresponding part of the 

 stomach. It receives numerous pancreatic veins from the pancreas. At the 



1 These branches are generally filled with blood and therefore easily traced. If they are empty, 

 they may be readily injected through the hepatic portal vein, even in specimens which have been 

 preserved for a long time. 



