DIGESTION. 



175 



HEPATIC LOBULE, in transverse section, showing the 

 distribution of its blood-vessels. a, a. Interlobular veins. 

 6. Intralobular vein, c, c, c. Plexus of capillary blood-vessels 

 within the lobule, d, d. Twigs of interlobular vein, passing 

 to adjacent lobules. 



inosculation a capillary plexus, the vessels of which have a general con- 

 vergent direction toward the centre of the lobule, 

 unite to form an efferent 



vessel, which, from its FIG. : 



position, is termed the 

 intralobular vein, and 

 which continues its course 

 until it joins a small branch 

 of the hepatic vein. Each 

 lobule is therefore a more 

 or less ovoid, cylindrical, 

 or prism - shaped mass, 

 resting upon a branch of 

 the hepatic vein. It is 

 attached to this vessel by 

 its own intralobular vein, 

 which passes through its 

 axis receiving the blood 

 collected from it ; while it 

 is encircled by terminal 

 branches of the portal vein, 

 which supply the blood 

 for its interior circulation. 



Beside its capillary 



blood-vessels, the lobule consists, mainly of glandular cells. These are 

 generally of a five- or six-sided prismatic form, often with one or two 

 of their borders excavated by curvilinear furrows at the points where 

 they are in contact with a capillary blood-vessel. They are, on the 

 average, 22 mniin. in diameter, finely granular, usually, in man, con- 

 taining one or more fat globules, and provided with a round or oval 

 nucleolated nucleus. The cells ore everywhere in contact with each 

 other by their plane surfaces, and each one is also in direct relation at 

 several points with a capillary blood-vessel. Thus the two elements 

 are intimately united throughout the substance of the lobule. 



There is an equally close connection between the glandular cells and 

 the biliary ducts. The main hepatic duet, which with its ramifications 

 accompanies the divisions of the portal vein, breaks up into branches 

 which finally reach the interlobular spaces. In man, the biliary ducts 

 of a larger diameter than about 200 mmm. are lined with cylindrical 

 epithelium ; while in those below 100 mmm. in diameter, the form of 

 the cells changes to that of pavement epithelium. The biliary duets 

 in the interlobular spaces are of the smaller variety, being not more 

 than 50 mmm. in diameter, and lined with pavement epithelium. They 

 break up into communicating branches, which cover the lobule with a 

 plexus of biliary canaliculi. 



From this superficial plexus the finest biliary tubes penetrate the 

 lobule and there inosculate with each other between the glandular cells. 



