THE VASCULAR SYSTEM (Continued) 

 THE HEPATIC PORTAL SYSTEM 



Prepare now to study the contents of the abdominal 

 cavity, that part of the coelom which lies posterior to the 

 diaphragm. Slit the abdominal wall in the sagittal plane 

 from the diaphragm posteriorly nearly to the external 

 genital organs, which lie between the hind legs. Do not 

 injure either the external or internal genital organs. Make 

 an anterior and a posterior cut at right angles to this longi- 

 tudinal incision, reflect the lateral flaps, exposing the di- 

 gestive and reproductive systems lying in the abdominal 

 cavity. Examine the mesenteries supporting the digestive 

 organs, and observe their veins. 



The portal system comprises the veins which carry to 

 the liver the blood from the capillaries of the intestines, 

 stomach, pancreas, and spleen. All the tributaries of this 

 system converge to the portal vein which goes into the 

 liver immediately ventral to the entrance of the inferior 

 vena cava into that organ. Trace the ramifications of the 

 portal system throughout the mesenteries of the stomach 

 and intestines. Just before it enters the liver the portal 

 vein receives the pancreatico-duodenal vein from the duo- 

 denum and pancreas, and the gastro-epiploic vei/n from the 

 pancreas and greater curvature of the stomach. These two 

 vessels unite and enter the portal vein by a common trunk. 

 The portal vein is formed by the confluence of the gastro- 

 splenic and superior mesenteric veins. The gastro-splenic 

 is formed by the union of branches from the spleen, pan- 

 creas, and lesser curvature of the stomach. The superior 



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