THE LIVER 



415 



FIG. 390. HUMAN 

 LIVER CELL, SHOW- 

 ING ENLARGED IN- 

 TRACELLTTLAR CAN- 

 ALICULI, A CONDI- 

 TION CHARACTERIS- 

 TIC OF JAUNDICE. 

 (Browicz.) 



Moreover, it seems probable that the canals described include structures 



of different significance. 



The Portal Canals. The portal canals are formed by the ramifica- 



tions of the portal vein, hepatic artery, and hep- 



atic 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 con- 



nective 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. The interlobular 



veins, branches of the portal, are extremely thin- 



walled sinusoidal 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. The interlobular arteries, branches 

 of the hepatic, are very small and are 

 noted for their highly developed mus- 

 cular coat and distinct elastic mem- 

 brane. They give off minute vaginal 

 branches which supply capillaries to 

 the tissue of Glisson's capsule. 



THE INTERLOBULAR BILE DUCTS. 

 The interlobular bile 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 interlobu- 

 lar veins and much more numerous 

 than the interlobular arteries. Due to 

 their frequent branching many of the 

 P rtal Is as seen in transverse sec- 

 tion contain two bile ducts. The ducts 

 are lined by columnar epithelium 



whose height varies with the size of the tubule, the smallest ducts being 



lined by low columnar, or cuboidal, the largest by tall columnar cells; 



FIG. 391. DIAGRAM OF A PORTAL 

 CANAL, INCLUDING A BRANCH OF 

 THE PORTAL VEIN, HEPATIC AR- 



MEDULLATED NERVE TRUNKS. 



