348 



STRUCTURE OF THE LIVER. 



The Hepatic Cells (Fig. 141, II, a) are irregular polygonal cells of about 

 th of an inch (34-45^) in diameter (Fig. 142). The arrangement of the capil- 

 laries within a lobule determines the arrangement of the liver-cells. The liver- 

 cells form anastomosing columns which radiate from the centre to the periphery 

 of each lobule (Fig. 143). [The liver-cells are usually stated to be devoid 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 contains a plexus of fibrils just like other 

 epithelial cells. In some animals, globules of oil and pigment granules are found 



Fig. 142. 



Human liver-cells the cell protoplasm con- 

 tains biliary colouring matter and oil- 

 globules b; d, has two nuclei. 



Fig. 143. 



Appearance of the liver- 

 cells after withholding 

 food for 36 hours. 



in the cell protoplasm (Fig. 142).] Each cell is in relation with the wide-meshed 

 blood-capillaries (d, d), and also with the much narrower mesh-work of bile 

 ducts (I, x.) 



It is important to observe that the appearance of the cells varies with the 

 period of digestion. During hunger, the liver cells are finely granular and very 

 cloudy (Fig. 143). About 13 hours after a full meal, especially of starchy food, 

 they contain coarse glancing masses of glycogen (Fig. 144, 2). The protoplasm 

 near the surface of the cell is condensed, and a fine net-work stretches towards the 

 centre of the cell, and in it is suspended the nucleus (Kupffer, Heidenhain). [The 

 net-work within the cells is best seen after solution of the glycogen.] 



4. The bile ducts. The finest bile capillaries or canaliculi arise from the 

 centre of the lobule, and indeed throughout the whole lobule, they form a regular 

 anastomosing net-work of very fine tubes or channels. Each cell is surrounded 

 by a polygonal usually hexagonal mesh (x, x). The bile capillaries always lie 

 in the middle of the surfaces between two adjoining cells (II, ft), where they form 

 actual intercellular passages (Hering). [According to some observers, they are 

 merely excessively narrow channels (1-2 mm. wide) in the cement-substance 

 between the cells, while according to others, they have a distinct delicate wall 

 (Fritsch). The bile capillary net-work is much closer and finer than the blood 

 capillary net-work. 



[Thus, there are three net-works within each lobule (1) a net-work of capil- 

 laries; (2) a net-work of hepatic cells; (3) a net-work of bile capillaries.] 



Excessively minute intracellular passages are said to pass from the bile 

 capillaries into the interior of the liver-cells, where they communicate with certain 

 small cavities or vacuoles (Asp, Kupffer, Pfliiger) (Fig. 144, 3). As the blood 

 capillaries run along the edges of the liver-cells, and the bile capillaries between 

 the opposed surfaces of adjacent cells, the two systems of canals within the 



