STRUCTURE OF THE LIVER. 



59. 



1. The Capsule. The liver is covered by a thin, fibrous, firmly-adherent capsule, which has 

 on its free surface a layer of endothelium derived from the peritoneum. The capsule sends fine 

 septa into the organ between the lobules, but it is also continued into the interior at the trans- 

 verse fissure, where it surrounds the portal vein, hepatic artery, and bile-duct, and accompanies 

 these structures as the capsule of Glisson, or interlobular connective-tissue. The spaces in 

 which these three structures lie are known as portal canals. In some animals (pig, camel, polar 

 bear) the lobules are separated from each other by the somewhat lamellated connective-tissue 

 of Glisson's capsule, but in man this is but slightly developed, so that adjoining lobules are 

 more or less fused. Very delicate connective-tissue, but small in amount, is also found within 

 the lobules. Leucocytes are sometimes found in the tissue of Glisson's capsule. 



2. Blood- Vessels. (a) Branches of the Venous System. The portal vein, after its entrance 

 into the liver at the portal fissure, gives oft' numerous branches lying between the lobules, and 

 ultimately forming small trunks which reach the periphery of the lobules, where they form a 

 rich plexus. These are the interlobular veins (figs. 188, 189, V.i). From these veins numerous 



X 



Fig. 189. 

 I, Scheme of a liver-lobule V.i, V.i, interlobular veins (portal); V.c, central or intralobular 

 vein (hepatic); c, c, capillaries between both; V.s, sublobular vein ; V.v, vena vascu- 

 laris ; A, A, hepatic artery, .giving branches, r, r, to Glisson's capsule and the larger vessels, 

 and ultimately forming the venae vasculares at i, i, opening into the intralobular capil- 

 laries; g, bile-ducts; x, x, intralobular biliary channels between the liver-cells; d, d, 

 position of the liver-cells between the meshes of the blood-capillaries. 1 1, Isolated, liver- 

 cells c, a blood-capillary ; a, fine bile-capillary channel. 



capillaries (c, c) are given off to the entire periphery of tne lobule. The capillaries converge 

 towards the centre of the lobule. As they proceed inwards, they form elongated meshes, and 

 between the capillaries lie rows or columns of liver-cells (d, d). The capillaries are relatively 

 wide, and are so disposed as to lie between the edges of the columns of cells, and never between 

 the surfaces of two neighbouring cells. The capillaries converge towards the centre of each 

 lobule, where they join to form one large vein, the intralobular, hepatic, or central vein ( V.c), 

 which traverses each lobule, reaches its surface at one point, passes out, and joins similar veins 

 from other lobules to form the sublobular veins (V.s). These in turn unite to form wide veins, 

 the origins of the hepatic vein, which opens into the vena cava inferior. 



(b) The branches of the hepatic artery accompany the branches of the portal vein and bile- 



