THE LIVER. 



179 







ulse which conform in their general disposition and shape to the intercapillary 

 spaces which they fill. When isolated, the liver-cells present a polygonal 

 outline and measure from 15-25 p. in their longest dimension. Eacn cell 

 comes into contact with from six to nine other ones, the surfaces of contact 

 being plane from mutual pressure. Always one side, often more than one, 

 exhibits a shallow concavity that indicates the surface of former contact with 

 a capillary. The cells lie against at least one capillary and sometimes several, 

 this relation depending upon the size of the blood-channel. The liver-cell 

 consists of finely granular protoplasm, which at times exhibits a differentiation 

 into an outer and inner zone. It is without a cell-membrane, although the 

 cytoplasm is condensed at the periphery. The spherical nucleus contains 

 relatively little chromatin and usually a nucleolus. Occasional cells are 

 conspicuous on account of their large size and unusually large nucleus; 

 such elements probably 

 undergo direct division 

 and produce the double 

 nucleated cells constant- 

 ly encountered in sec- 

 tions of normal liver. 

 Centrosomes have also 

 been observed. Particles 

 of glycogen, minute oil 

 drops, and granules of 

 bile- pigment are fairly 

 constant inclusions. Fat- 

 containing cells are most 

 abundant at the periph- 

 ery of the lobule, those 

 containing pigment par- 

 ticles near the centre. 



The Bile-Capil- 

 laries. These minute 

 canals, representing the 

 lumina of ordinary tubu- 

 lar glands, form a network of intercommunicating channels throughout 

 the lobule, closely related to the liver-cells. Instead of the arrangement 

 usual in glands, where several secreting cells border the gland-lumen each 

 with a single surface, in the exceptional case of the liver the excretory 

 channels are bounded by the opposed surfaces of only two cells, the 

 bile-capillary occupying but a small part of these surfaces, which it 

 models with a narrow groove. Moreover, the canaliculi are not limited to a 

 single surface on each cell, for they are found between all surfaces where 

 two liver-cells are directly in contact. Hence, each hepatic cell is in imme- 

 diate relation with a number of bile-capillaries. The latter, however, never 

 lie on the surfaces of the liver-cells directed towards the blood-channel, the 

 bile-canaliculus never separating the blood-capillary and the liver-cell. 

 Whilst the dominating direction of the bile-capillaries is radial and corre- 

 sponds to the general disposition of the trabeculae of hepatic cells, this radial 

 arrangement is converted into a network by numerous cross-branches (Fig. 

 224). The resulting meshes agree in size and form with the individual liver- 

 cells, which often appear surrounded by the bile-capillaries. The latter 

 possess no walls other than the substance of the liver-cells between which 

 they lie. The diameter of the minute biliary canals (1-2 /.*) remains con- 



FIG. 222. Section of uninjected liver, showing cords of hepatic cells 

 between the capillary blood-vessels. X 400. 



