532 



SPECIAL HISTOLOGY. 



Fig. 220. 



160. Hepatic cells and cell-networks. Every hepatic islet contains 

 two elements ; 1, a network of capillaries, which, on the one hand, is 

 continuous with the finest portal branches, and on the other, unites into 

 the intralobular vein, one of the roots of the hepatic vein ; and 2, an 

 interlaced tissue of delicate columns, composed of nothing but cells, the 

 so-called hepatic cells, in close and immediate apposition. These two 

 networks are so interwoven that the interstices of the one are completely 

 filled by the solid portions of the other and leave no interspaces, at least 

 when the vessels contain blood or are injected. Not a trace of biliary 

 ducts is to be observed in this network : they are first met with at the 

 periphery of the hepatic islets, where also the finest portal branches 

 occur, without its having been possible, hitherto, to make out, directly, 

 their connection with the hepatic-cell-network, which is indubitably the 

 secreting portion of the liver. 



The hepatic cells, which may be isolated with the greatest ease,* have 

 a diameter of 0-008-0-012 of a line on the average, 0-006-0-016 of a 

 line in extreme cases, and resemble tessellated epithelium-cells in form, 

 except that they are more irregular. Their membrane is delicate, and 



perfectly closed, and their con- 

 tents, in perfectly normal livers, 

 such as are rarely met with in 

 man, but readily enough in ani- 

 mals, are a granular, yellowish, 

 semifluid substance, which, as 

 microscopic investigation shows, 

 probably contains the essential 

 element of the bile. In this lies a 

 round vesicular nucleolated nu- 

 cleus, of 0-003-0-004 of a line ; 

 and in many cells there are two. 



Besides these, fat-drops and pigment granules are frequently to be met 

 with. The former (Fig. 220 e) occur in all the cells, when the liver has 

 undergone fatty degeneration, in such quantities that they become very 

 similar to certain forms of fat-cells ; and generally, as a few large or 

 many small drops, entirely fill the cell, so that the nucleus becomes invi- 



FIG. 220. Hepatic cells of Man, magnified 400 diameters : a, more normal cells ; 6, with 

 pigment ; c, with fat. 



* [This is true of the hepatic " cells*' of Man and many Mammalia, but not of all. In the 

 Rat, we could find no demarcation of the hepatic tissue into cells, the tissue resembling very 

 nearly that of the spleen. In Fishes, Dr. Handfield Jones has pointed out the existence of 

 all varietes in this respect, from free " nuclei," with oily and granular matter scattered through 

 a matrix, up to perfectly formed "cells." In the Pigeon, the same author finds no fully 

 formed cells, nor in the Duck; and he therefore draws the general conclusion, "that the 

 secreting process by no means requires the formation of perfect cells in order to effect its 

 peculiar changes; these may certainly occur in blastematous matter, if the nucleus only be 

 present." "Philosoph. Transactions," 1849, p. 132. TES.] 



