STRUCTURE OF THE LIVER. 



679 



The fibrous coat lies beneath the serous investment, and covers the entire 

 surface of the organ. It is difficult of demonstration, excepting where the serous 

 coat is deficient. At the transverse fissure, it is continuous with the capsule of 

 Glisson ; and, on the surface of the organ, with the areolar tissue separating the 

 lobules. 



The lobules form the chief mass of the hepatic substance ; they may be seen 

 either on the surface of the organ, or by making a section through the gland. 

 They are small granular bodies, about 

 the size of a millet-seed, measuring from 

 one-twentieth to one-tenth of an inch in 

 diameter. When divided longitudinally, 

 they have a foliated margin, and, if trans- 

 versely, a polygonal outline. The bases 

 of the lobules are clustered round the 

 smallest branches (sublobular) of the 

 hepatic veins, to which each is connected 

 by means of a small branch, which issues 

 from the centre of the lobule (intra- 

 lobular). The remaining part of the sur- 

 face of each lob ale is imperfectly isolated 

 from the surrounding lobules, by a thin 

 stratum of areolar tissue, and by the 

 smaller vessels and ducts. 



If one of the hepatic veins be laid 

 open, the bases of the lobules may be 

 seen through the thin wall of the vein, 

 on which they rest, arranged in the form 

 of a tessellated pavement, the centre of 

 each polygonal space presenting a mi- 

 nute aperture, the mouth of a sublobular 

 vein. 



Each lobule is composed of a mass of 

 cells ; of a plexus of biliary ducts ; of a 

 venous plexus, formed by branches of 

 the portal vein ; of a branch of an he- 

 patic vein (intralobular); of minute 

 arteries ; and probably, of nerves and 

 lymphatics. 



The hepatic cells form the chief mass 

 of the substance of a lobule, and lie in 

 the interspaces of the capillary plexus, 

 being probably contained in a tubular 

 network, which forms the origin of the 

 biliary ducts. The smallest branches of 

 the vena portae pass between the lobules, 

 around which they form a plexus, the 

 interlobular. Branches from this plexus 

 enter the lobules, and form a network in 

 their circumference. The radicles of the 

 portal vein communicate with those of 

 the hepatic vein, which occupy the centre 

 of the lobule ; and the latter converge to 

 form the intralobular vein, which issues 

 from the base of the lobule, and joins the 

 hepatic vein. The portal vein carries 

 the blood to the liver, from which the 

 bile is secreted; the hepatic vein carries 



H. Longitudinal section of an hepatic vein ; n, por- 

 tion of the canal, from which the vein has beeu 

 removed ; 6, orifices of ultimate twi^s of the vein 

 (sub-lohular), situated in the centre oi'the lobules. 

 After Kiernau. 



Fig. 344. 



Longitudinal section of a small portal vein and 

 caual, after Kiernan. a. Portions of the caual 

 from which the vein has been removed ;: B, side 

 of the portal vein in contact with the canal; 

 c, the side of the vein which is separated from 

 the canal by the hepatic artery and d'uct, with 

 areolar tissue (Glisson's capsule); d, internal sur- 

 face of the portal vein, through which are seen 

 the outlines of the lobules and the openings of 

 the interlobular veins ; /, vaginal veins of Kie 

 nan ; g, hepatic artery ; ^ hepatic duct. 



