THE PORTAL CAXALS 329 



duct, and are characteristic of the liver, the peculiarity consisting 

 not so much in the structure of the tissue, as in the combination 

 of artery, duct, and vein occurring in close relation, in the connect- 

 ive tissue at the angles of the hepatic lobules. The largest vessel 

 in the canal is invariably the vein, the smallest the artery. 



The Interlobular Veins, branches of the portal, are extremely 

 thin-walled vessels. They are formed by scarcely more than the 

 endothelial lining, which is supported by the connective tissue of 

 Glisson's capsule. Their wall contains very little or no smooth 

 muscle. 



The Interlobular Arteries, branches of the hepatic, are very 

 small and are noted for their highly developed muscular coat and 

 distinct elastic membrane. They give off minute vaginal branches 

 which supply capillaries to the tissue of Glisson's capsule. 



* - .-,-* 



V - " ^ ^ 





FIG. 273. A PORTAL CANAL OF THE HUMAN LIVER. 



The large thin- walled vessel in the center of the connective tissue is the interlobular 

 vein ; at its left are two ducts in oblique and longitudinal section ; at the right of the 

 vein, a duct and an artery are seen in transection. Hematein and eosin. Photo, x 375. 



The Interlobular Ducts, radicals of the hepatic duct, receive 

 the bile from the intralobular bile canaliculi and convey it, through 

 larger and larger branches, to the hepatic duct. They are more 

 numerous than the interlobular veins and much more numerous 



