200 



STRUCTURE OF THE LIVER. 



duct in the portal canals between the lobules, and in their course give off capillaries to supply 

 the walls of the portal vein and larger bile-ducts. The branches of the hepatic artery anasto- 

 mose frequently where they lie between the lobules. On reaching the periphery of the lobules, 

 a certain number of capillaries are given off, which penetrate the lobule and terminate in the 

 capillaries of the portal vein (i, i). These capillaries, however, which supply the walls of the 

 portal vein and large bile-ducts (r, r), terminate in veins which end in the portal vein (V.v). 

 Several branches capsular pass to the surface of the liver, where they form a wide-meshed 

 plexus under the peritoneum. The blood is returned by veins, which open into branches of the 

 portal vein. 



[Hepatic Zones. Pathologists draw a sharp distinction between different zones within a 

 hepatic lobule. Thus the central area, capillaries, and cells form the hepatic vein zone, which 

 is specially liable to cyanotic changes ; the area next the periphery of the lobule is the portal 



Fig. 190. 



Human liver-cells containing oil-globules, b 



d, has two nuclei. 



Fig. 191. 

 Liver-cells after withholding food for 

 36 hours. 



vein zone, whose cells under certain circumstances are particularly apt to undergo fatty de- 

 generation ; while there is an area lying midway between the two foregoing the hepatic 

 artery zone which is specially liable to amyloid or waxy degeneration.] 



3. The hepatic cells (fig. 189, II, a) are irregular polygonal cells of about TTnnrtli of an inch 

 (34 to 45 /x) in diameter (tig. 190). The arrangement of the capillaries within a lobule deter- 

 mines the arrangement of the 

 Finest bile-duct. Finest bile-duct divided. liver-cells. The liver-cells 



form anastomosing columns 

 which radiate from the centre 

 to the periphery of each lobule 

 (fig. 191). [the liver-cells 

 are usually stated to be de- 

 void of an envelope, although 

 Haycraft states that they 

 possess one. They usually 

 contain a single nucleus, with 

 one or more nucleoli, but 

 sometimes two nuclei occur. 

 The protoplasm and nucleus 

 of each cell contain a plexus 

 of fibrils just like other epi- 

 thelial cells. In some animals, 

 globules of oil and pigment- 

 granules are found in the 

 cell-protoplasm (fig. 190). 

 Each cell is in relation with 

 the wide-meshed blood-capil- 

 laries (d, d), and also with 

 the much narrower mesh work 

 of bile-ducts (I, x). 



Changes in Liver-Cells. 

 The appearance of the eells 

 varies with the period of di- 

 gestion. During hunger, the liver-cells are finely granular and very cloudy (fig. 191), [and 

 contain little glycogen, but many pigment-granules, and the nucleus is more frequently absent. 

 Often free nucleoli and pale nuclei are found (Mlenberger and Baum). During activity, i.e., 

 after a full meal, especially of starchy food, the cells are larger and more distinct, stain more deeply 

 with eosin, and contain fewer granules]. The protoplasm contains coarse, glancing masses of 

 glycogen (fig. 194, 2), and near the surface of the cell it is condensed, and a fine network stretches 



Nucleus of a Finest 

 liver-cell. bile-duct. 



Fig. 192. 



Blood-capillaries : finest bile-ducts in their relative position in a 



rabbit's liver. 



