324 THE LIVER 



columns of liver cells are suspended. The anastomosing strands 

 of reticulum converge from the periphery toward the center of 

 the lobule, thus following the course of the blood capillaries and 

 cell columns. This reticular tissue (Mall) exists in so small a 

 quantity and is so extremely delicate that although it can be 

 readily studied after removal of the liver cells, as by artificial 

 digestion, in ordinary preparations, except those of extreme thin- 

 ness, it can scarcely be discovered in the minute clefts between 

 the cell columns and the blood capillaries. 



The volume of the interlobular connective tissue which forms 

 Glisson's capsule varies greatly in different animals. In the liver 

 of the pig this tissue is very extensive and forms a complete 

 investment for each lobule. In man it is very limited in amount 

 and is confined to minute areas between the .adjacent angles of 

 the lobules, with an occasional fragment separating the lateral 

 surfaces of neighboring lobules. It is in the latter portions, viz., 

 between the opposed surfaces of the lobules, that the branches of 

 the hepatic veins (sublobular veins) are found. The interlobular 

 veins, the subdivisions of the portal vein, together with the bile 

 ducts and the branches of the hepatic artery are found at the 

 angles of adjacent lobules ; hence the portal canals, which contain 

 these vessels, should always be sought in this location, while 

 the sublobular veins, which run alone and form no part of the 

 portal canals, will be found between the opposed surfaces of the 

 lobules. 



The capsule of Glisson also contains many lymphatic vessels 

 and non-medullated nerve fibres. 



THE HEPATIC LOBULE. The lobule is the structural unit 

 of the liver and consists chiefly of hepatic cells which are arranged 

 in radiating columns. In shape the lobule is an irregularly hex- 

 agonal pyramid, the exact number of its faces being extremely 

 variable. The periphery of the lobule is outlined by the connect- 

 ive tissue of Glisson's capsule which either completely invests 

 each lobule, as in the pig's liver, or forms only a very incomplete 

 investment, as in the liver of man. 



Blood enters the lobule from the vessels of the portal canals 

 and finds its way, through converging capillaries, from the periph- 

 ery to the center of the lobule. Here it enters the intralobular 

 or central vein, which occupies the axis of the lobule and conveys 

 the blood thence to the sublobular veins, which again lie in the 

 interlobular connective tissue of Glisson's capsule. 



