528 



THE LIVEK 



[CH. XXXV. 



form, but somewhat polygonal from mutual pressure. Each possesses 

 a nucleus, sometimes two. The cell protoplasm contains numerous 

 fatty particles, as well as a variable amount of glycogen. 



The portal vein, hepatic 

 artery, and hepatic duct, run 

 in company, and their appear- 

 ance on longitudinal section is 

 shown in fig. 362. Eunning 

 together through the substance 

 of the liver, they are contained 

 in small channels called portal 

 canals, their immediate in vest- 

 ment being a sheath of areolar 

 tissue continuous with Glis- 

 son's capsule. 



In its course through the 

 liver the portal vein gives off 

 small branches which divide 

 and subdivide between the 

 lobules surrounding them and 

 limiting them, and from this 

 circumstance called inter- 

 lobular veins. From these 

 vessels a dense capillary net- 

 WOrk is prolonged into the 

 i . is J_T_ i i_ i 



substance of the lobule, and 

 this network converges to a 



single small vein, occupying the centre of the lobule, and hence 

 called m^ra-lobular. This arrangement is well seen in fig. 363, 

 which represents a section of a small piece of an injected liver. 



The mra-lobular veins discharge their contents into veins called 

 sw&-lobular; these by their union, form the main branches of the 

 hepatic veins, which leave the posterior border of the liver to end 

 by two or three principal trunks in the inferior vena cava, just 

 before its passage through the diaphragm. 



The so-called capillaries of the liver are really sinusoids (see p. 

 222); they are in direct contact with the liver-cells, and are not 

 surrounded with lymph spaces as in other secreting glands; their 

 endothelial covering is in many places incomplete, and its cells are 

 irregularly branched and more or less isolated from their neighbours. 

 They are called the stellate cells of Kupffer. The result is that the 

 blood comes into direct contact with the liver-cells. 



The hepatic artery, the chief function of which is to distribute 

 blood for nutrition to Glisson's capsule, the walls of the ducts and 

 blood-vessels, and other parts of the liver, is distributed in a very 



FIG. 362. Longitudinal section of a portal canal, con- 

 taining a portal vein, hepatic artery and hepatic 

 duct, from the pig. P, Branch of vena portse, 

 situated in a portal canal amongst the lobules of 

 the liver; I, I, and giving off interlobular veins; 

 there are also seen within the large portal vein 

 numerous orifices of interlobular veins arising 

 directly from it ; a, hepatic artery ; d, bile duct, 

 x 5. (Kiernan.) 



