168 



NORMAL ANATOMY OF THE LIVER. 



and hepatic artery, and the interlobular spaces are 

 supplied solely with branches which are derived 

 fiom its ramifications. But in the smaller por- 

 tal canals (fig. 37, Jig. 38) the capsule of Ghs- 

 son, upon which the plexus chiefly depends, is 



Fig. 37. 



Fig. 38. 



A transverse section of a small portal canal and its ves- 

 sels. The lobules are in a state of general congestion. 

 From Kier nan's paper. 



No. 1, The portal vein ; the greater part of its 

 cylinder is in contact with the portal canal. 2, In- 

 terlobular branches of the vein entering directly the 

 interlobular spaces, with branches of the artery and 

 duct, without ramifying in the canal. 3, Two vagi- 

 nal branches arising from the vein, and forming a 

 vaginal plexus on that side of the vein, which is 

 separated from the canal by Glisson's capsule. 

 From the plexus the interlobular branches arise. 

 4, The hepatic duct giving off vaginal branches. 5, 

 The artery giving off vaginal branches. Glisson's 

 capsule is situated on one side only of the canal. 



situated only upon that side of the vein, on 

 which the duct and artery are placed, and the 

 vaginal plexus consequently follows the same 

 disposition. On the opposite side the portal 

 vein being in contact with the lobules, gives off 

 interlobular branches directly to the spaces. If 

 the portal vein (Jig. 38) be laid open in this 

 situation, the form of the lobules bounded by 

 the interlobular fissures will be distinctly ap- 

 parent through its coats, and the openings of the 

 interlobular veins will be found to correspond 

 with the interlobular spaces. 



The interlobular veins enter the intervals of 

 the lobules through the interlobular spaces and 

 divide into numerous minute branches, which 

 ramify in the capsules of the lobules and then 

 enter their substance. They cover with their ra- 

 mifications the whole external surface of the lo- 

 bules with the exception of their bases, and of 

 those extremities of the superficial lobules which 

 appear upon the surfaces of the liver. The 

 interlobular veins communicate freely with each 

 other and with the corresponding branches of 

 adjoining lobules, and establish a general 

 portal anastomosis of the freest kind through- 

 out the entire liver. When the portal vein is 

 well injected, these veins form a series of inos- 

 culations which surround all the lobules and 

 give to the surface of the organ the appearance 

 of a vascular network composed of irregularly 

 pentagonal and hexagonal meshes. If the vein 

 be only partially injected the interlobular vein 

 in the interlobular space is alone filled, and the 

 branches which it sends off into the neighbour- 



Longitudinal section of a small portal vein and canal. 

 The lobules are in a state of aneemia. After Kier- 



nan. 



a, Portions of the canal from which the vein is 

 removed to show that it is formed by lobules which 

 present the same appearance with those upon the 

 external, surface of the liver, b, The side of the 

 portal vein which is in contact with the canal, c, The 

 side of the vein which is separated from the canal 

 by the hepatic artery and duct, by the Glisson's 

 capsule surrounding them, and by the vaginal plexus. 

 d, The internal surface of the portal vein, through 

 which is seen the outline of the lobules, and the 

 openings of the interlobular veins which correspond 

 with the interlobular spaces. Upon the opposite 

 side (c), the portal vein being separated from the 

 portal canal there are no interlobular veins, e, The 

 openings of smaller portal veins, f, Vaginal veins 

 giving off branches in the portal canal and forming 

 a plexus, g. The hepatic artery giving off vaginal 

 branches, h, The hepatic duct giving off vaginal 

 branches. 



ing interlobular fissures not proceeding so far 

 as to inosculate and form meshes, have a 

 radiated appearance and resemble a number of 

 minute stellae ; these are the stellated vessels of 

 anatomists. 



The lobular veins are derived from the inter- 

 lobular veins ; they form a plexus within 

 the lobule, and converge from the circum- 

 ference towards the centre, where they terminate 

 in the minute branches of the intralobular vein. 

 " This plexus, interposed between the inter- 

 lobular portal veins and the intralobular hepatic 

 vein, constitutes the venous part of the lobule, 

 and may be called the lobular venous plexus." 

 (Jig- 39). The irregular islets of the substance 

 of the lobules seen between the meshes of this 

 plexus by means of the microscope are the 

 acini of Malpighi, and are shown by Kiernan 

 to be portions of the lobular biliary plexus. 



The portal vein collects the venous blood 

 from the chylopoietic viscera, and then circu- 

 lates it through the lobules ; it likewise receives 

 the venous blood which results from the distri- 

 bution of the hepatic artery to the structures of 

 the liver; these two sources of supply constitute 

 the two origins of the portal vein, the abdominal 

 origin and the hepatic origin. 



