STRUCTURE OF THE LIVER. 



101 



Fig. 152.* The hepatic arteries, distribute 



,-^ their branches in the coats of the 

 hepatic ducts, venae portarum 

 and hepatic veins ; and the veins 

 in which these arterial capil- 

 ^ laries terminate, always consist, 

 according to Mr. Kiernan, of 

 the radical branches of the vena 

 portarum. Thus, the hepatic 

 arteries and the portal branches, 

 form the vasa vasorum of all 

 the different vessels and ducts of the liver ; and all the blood of 

 the hepatic arteries, passes first into the portal system and 

 thence into the hepatic veins, in its circulation through the liver. 

 For these reasons, Mr. Kiernan believes the bile to be secreted 

 solely from the blood of the portal veins. For even in the well 

 known case mentioned by Mr. Abernethy, where the vena porta 

 terminated in the vena cava without passing through the liver, 

 he found the hepatic arteries much larger than usual, and the 

 portal branches into which they terminated in their course 

 through the liver of corresponding development; so that 

 even in anomalous cases of that description, the biliary secre- 

 tion is made not from arterial blood, but from that of the portal 

 veins. The capsule of Glisson is a cellular sheath which extends 

 around the hepatic artery, vein and duct, accompanying their 

 minutest ramifications up to the lobules, and terminates by- 

 forming a delicate capsular investment to each of the individual 

 lobules. It serves, according to Kiernan, like the pia mater of 

 the brain, as a nidus or bed in which the larger branches of 

 the vessels may subdivide before entering into the delicate 

 structure of the lobules. In the interlobular spaces, filled up 

 with this tissue, the portal veins form a sort of vascular circle 

 as seen in fig. 148. 



* Fig. 152, A, An hepatic vein. B, Lobules arranged around the intralobular 

 branches of the hepatic veins, as they are frequently seen at the posterior part 

 of the concave surface of the liver. This arrangement is more distinctly seen 

 in the liver of the sheep than in the human liver. These lobules are parallel to 

 the surface. 



9* 



