STRUCTURE OF THE LIVER. 



745 



hepatic duct, hepatic artery, hepatic veins, 

 lymphatics, and nerves; the whole being in- 

 vested by a fibrous and a serous coat. 



The serous coat is derived from the perito- 

 neum, and invests the entire surface of the 

 organ, excepting at the attachment of its 

 various ligaments, and at the bottom of the 

 different fissures, where it is deficient. It is 

 intimately adherent to the fibrous coat. 



The fibrous coat lies beneath the serous in- 

 vestment, and covers the entire surface of the 

 organ. It is difficult -of demonstration, ex- 

 cepting 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 he- 

 patic 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. If divided 

 longitudinally, they have a foliated, and, if 

 transversely, 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 (intralobular). The remaining part of 

 the surface of each lobule is imperfectly iso- 

 lated 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 pave- 

 ment, the centre of each polygonal space pre- 

 senting a minute 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 hepatic 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 inter- 

 spaces 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 cir- 



Fig. 409. 

 H 



H. Longitudinal section of an hepatic vein. 

 . Portion of the canal, from which the 

 vein has been removed ; b, orifices of ulti- 

 mate twigs of the vein (sublobular), situ- 

 ated in the centre of the lobules. After 

 Kiernan. 



Fig. 410. 



Longitudinal section of a small portal vein 

 and canal, after Kiernan. a. Portions of 

 the canal 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 duct, with are- 

 olar tissue (Glisson's capsule) ; d, inter- 

 nal surface of the portal vein, through 

 which are seen the outlines of the lobules 

 and the openings (<?) of the interlobular 

 veins ;/, vaginal veins of Kiernan ; g, he- 

 patio artery ; h, hepatic duct. 



