NORMAL ANATOMY OF THE LIVER. 



169 



Fig. 39. 



Two lobules, in which the portal venous plexus is seen. 

 After Kiernan. 



a a, Interlobular veins. The appearance of venous 

 circles formed by these veins is that which is 

 afforded by a common lens ; when examined with 

 a higher power the interlobular fissure is seen to be 

 filled by a vascular plexus, b, The lobular venous 

 plexus. The circular and ovoid spaces seen be- 

 tween the branches of the plexuses are occupied by 

 portions of the biliary plexus : they are the acini 

 of Malpighi. c. The intralobular vein in the centre 

 of each lobule, collecting the blood from the lobu- 

 lar venous plexus. 



The hepatic duct bifurcates in the transverse 

 fissure into two branches, which enter the right 

 and left lobes of the liver and subdivide into 

 smaller branches, and the smaller branches 

 accompany the divisions of the portal vein and 

 hepatic artery through the portal canals to their 

 ultimate distribution in the lobules. The 

 branches of the hepatic duct, like those of the 

 portal vein, are divisible into the vaginal, inter- 

 lobular, and lobular ducts. 



The vaginal ducts pass transversely through 

 the capsule of Glisson, by which they are enve- 

 loped in common with the portal vein and 

 hepatic artery, and divide into numerous small 

 branches which assist in forming the vaginal 

 plexus. From the plexus of ducts two kinds 

 of branches are given off, the interlobular, 

 which run along the margins of the interlobular 

 fissures and enter the interlobular spaces to be 

 distributed upon the capsular surfaces of the 

 lobules ; and the lobular, which enter the sub- 

 stance of those lobules which form the parietes 

 of the portal canals. In the smaller portal 

 canals the vaginal branches and plexus are 

 situated only on the portal side of the canal, 

 the interlobular branches, on the side nearest 

 the duct, passing directly into the interlobular 

 spaces. " The transverse branches and those 

 which arise immediately from them do not 

 anastomose with each other, but the smaller 

 branches sometimes appear to do so; I cannot, 

 however," says Kiernan, " from dissection, 

 affirm that they do, for those which appear to 

 anastomose are exceedingly small vessels and 

 meet each other at the spaces, hence it is diffi- 

 cult to ascertain whether they really anastomose 

 or enter the spaces together without anasto- 

 mosing," 



The interlobular ducts ramify upon the cap- 

 sular surface of the lobules with the branches 

 of the portal vein and hepatic artery. Kiernan 

 finds these ducts to communicate freely with 

 each other, for he says, " If the left hepatic 

 duct be injected with size or mercury, the injec- 

 tion will return by the right duct without extra- 

 vasation and without passing into other vessels, 

 and the injection will be found in the inter- 

 lobular and vaginal ducts as well as in the 

 trunks. This communication between the two 

 ducts does not take place like that which exists 

 between the right and left arteries through the 

 medium of the vaginal branches of the trans- 

 verse fissure, the injection being found in inter- 

 lobular branches arising from the right duct. 

 From this experiment, which I have frequently 

 repeated with the same result, it appears that 

 the right and left duct anastomose with each 

 other through the medium of the interlobular 

 ducts. This experiment does not always suc- 

 ceed, which probably arises from the quantity 

 of bile contained in the ducts." 



The lobular ducts entering the lobule by its 

 circumference divide and subdivide into minute 

 branches which anastomose with each other 

 and form a " reticulated plexus," the lobular 

 biliary plexus (jig. 40). This plexus consti- 



Fig. 40. 



p.^<.^a u a |\ 



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 " :^ 



Two lobules in which the lobular biliary plexus it 

 shewn. After Kiernan. 



a a, Inteilobular ducts giving off branches which 

 form the plexus within the lobules. The central 

 portion of the lobules is uninjected. 6 b, The rami- 

 fications of the intralobular veins. With regard to 

 this figure Kiernan observes, " No such view of 

 the ducts as that represented in this figure can be 

 obtained in the liver. The interlobular ducts are 

 in the figure seen anastomosing with each other. I 

 have never seen these anastomoses, but I have 

 seen the anastomoses of the ducts in the left lateral 

 ligament, and from the results of experiments re- 

 lated in this paper, I believe the interlobular ducts 

 anastomose. 1 have never injected the lobular 

 biliary plexuses to the extent represented in the 

 figure." 



tutes the principal part of the substance of the 

 lobule, and seen through the meshes of the 

 portal venous plexus, gives rise to the appear- 

 ance of acini or of coecal terminations of ducts. 

 The ultimate terminations of the ducts have 

 not yet been seen ; they are imagined by 

 Miiller to end in " short pannicle-like tufts 

 closely interwoven together," and he supports 

 his opinion by citing the circumstance of the 

 ducts in the embryo of the fowl and larva of 



