166 



STUDENTS HISTOLOGY 



best seen when the lobules have been divided in a vertical di- 

 rection. 



The bile -capillaries are among the smallest canals found in vas- 

 cular tissues, having a diameter of only 1 to 2 /*. They pursue a 

 direction in the human liver, as a rule, at right angles to the course 

 of the blood -capillaries, and are not demonstrable, except with 

 considerable amplification, say X 400, and then only in the 

 thinnest portion of the sections. They are, properly speaking, 

 merely minute channels in the parenchyma, and have, it is 

 believed, no wall. 



The hepatic cells are polyhedral, about twice the size of a white 

 blood-corpuscle, say from 20 to 25 ^ i n diameter, usually with a 

 single nucleus and with granular protoplasm, frequently contain- 



FIG. 108. 



DIAGRAM ILLUSTRATING THE INTRALOBULAR 

 HISTOLOGY OF THE LIVER. 



The hepatic cells are connected in columns between the blood-capillaries. The cells are 

 endowed with the power of selecting especially such materials from the blood as are necessary 

 for 'the manufacture of bile. Having accomplished this, the secreted fluid is given up to the 

 bile-capillaries, and by them poured into the ducts, and led out of the liver for subsequent use. 

 The direction of the pressure is indicated by the arrows. This is the histology of gland-struc- 

 tures generally. 



ing minute fat-droplets and granules of yellow pigment. The ex- 

 istence of a definite limiting membrane has been questioned, as far 

 as the cell of the human liver is concerned, although such a 

 structure can be shown in many of the lower animals. 



The physiological plan of the intralobular structure is expressed 

 in the diagram, Fig. 108. The blood is brought into relation with 

 the lobular parenchyma the hepatic cells by the capillary plexus, 



