498 



TEE DIGESTIVE APPARATUS IN MAMMALIA. 



adipose granules, the volume and quantity of which vary with the condition 

 of the animals, or the period of digestion at which the liver is examined. The 

 hepatic cells are situated in the network formed by the vessels of the lobule, and 

 constitute its principal portion. 



Hepatic Z>Wi?/5.^^Destined to carry away the bile secreted in the interior 

 of the hepatic lobule, the biliary ducts form around it a kind of girdle that 

 accompanies the interlobular branches of the vena portag. Within and without, 

 this girdle sends off small prolongations ; the first bring it into communication 

 with the ducts of the neighbouring lobules ; the second pass to the centre of the 

 lobule, or they surround each cell. 



The wall of the biliary ducts is a thin amoi-phous membrane, lined, near the 

 periphery of the lobule, by polygonal cells, smaller than the hepatic cells, and, 

 beyond, by a kind of endothelium or cuticle. 



Afferent vessels. — These are the branches of the portal vein and hepatic artery. 

 The portal vein, after reaching the interior of the liver, divides into gradually 

 decreasing vessels, until it terminates in forming the interlobular veins. These 



Fia. 295. 



A, portion of a hepatic column, showing its compo- 

 nent secreting cells. B, Secreting cells detached: 

 a, In their normal state ; 6. a cell more highly 

 magnified, showing the nucleus and distinct oil- 

 particles ; c, in various stages of fatty degenera- 

 tion. 



BILIARY CAPILLARIES OP 

 THE rabbit's liver. 

 PART OF A LOBULE, 

 SHOWING THE AKRANGE- 



ment of the biliary 

 ducts in relation to 

 the hepatic cells. 



a, Capillaries of the biliary 

 ducts; 6, hepatic cells; 

 c, biliary ducts; d, ca- 

 pillary blood-vessels. 



vessels surround the lobule, communicate with the neighbouring interlobular 

 veins, and give off a large number of twigs to the interior of the lobule, where 

 they anastomose, and constitute the hepatic capillary plexus. The hepatic artery 

 furnishes ramuscules, which mix with the ramifications of the portal vein in the 

 (vaginal) plexus. The principal branches of the latter are all directed from the 

 periphery towards the centre of the lobule, where they unite to form the afferent 

 vessel. It results from this arrangement that the hepatic cells which fill the 

 spaces between the vessels, are placed in radiating series. 



Efferent vessel. — Situated in the centre of the lobules, this vessel receives all 

 the ramifications of the capillary plexus, and is named the intra-lohular or central 

 sublobular vein. It is voluminous, and communicates with the other intra-lobular 

 veins. (These intra-lobular veins terminate in the larger trunks that run along 

 the bases of the lobules, and are named the sublobular veins.) 



Lymphatics. —In a hepatic lobule are found very fine lymphatic vessels that 



