NORMAL ANATOMY OF THE LIVER. 



171 



papillae that is to be attributed the facility with 

 which Soemmering and other anatomists in- 

 jected the ducts from the arteries and veins, 

 and not to any direct communication between 

 the vessels and the ducts." 



The mucous lining of the ducts is provided 

 with a considerable number of muciparous 

 follicles which mingle their secretion with the 

 bile during its passage along the excretory 

 tubes. These follicles have been described by 

 all anatomists as existing in the larger ducts, 

 but they were not known to be present in the 

 smaller branches until they were discovered and 

 figured by Kiernan. In the larger ducts they 

 are irregularly dispersed, but in the smaller 

 tubes are found arranged in two longitudinal 

 rows upon opposite sides of the ducts. Hence 

 the vascularity of the hepatic ducts is intended 

 to perform a higher function than the mere 

 nutrition of those tubes; it provides an im- 

 portant secretion as an auxiliary to the compo- 

 sition of the bile. 



The hepatic artery arises from the creliac 

 axis and ascends through the right border of 

 the lesser omentum to the transverse fissuie of 

 the liver, where it bifurcates into two branches 

 for the right and left lobes. The right and left 

 hepatic arteries ramify in the portal canals, and 

 give off branches which accompany each twig 

 of the portal vein and hepatic duct. Their 

 brandies, like those of the vein and duct, are 

 the vaginal, the interlobular, and the lobular. 



The vaginal arteries arise from the hepatic 

 arteries in the portal canals, and assist in form- 

 ing the vaginal plexus in the capsule of Glisson, 

 from which the interlobular branches are given 

 off to accompany the interlobular portal veins 

 and ducts. In the larger canals the plexus 

 completely surrounds the portal vessels, but in 

 the smaller canals the plexus is situated only 

 on the side opposite to the cylinder of the 

 artery, and in the tissue of Glisson's capsule. 

 This vaginal plexus has the effect of supplying 

 the lobules which are the most distant from the 

 vessel to which they belong, as certainly, as those 

 which are in immediate contact with its cylin- 

 der. The vaginal arteries anastomose so freely 

 with each other, that if the hepatic artery of 

 one side be injected, the injection will return by 

 that of the opposite side. 



The interlobular arteries enter the intervals 

 of the lobules through the interlobular spaces 

 and ramify upon the capsular surface of the 

 lobules. They are distributed principally to 

 the interlobular ducts, around which they form 

 a vascular net-work. The question of the 

 inosculation of these vessels is very difficult to 

 decide by dissection on account of their ex- 

 treme minuteness ; but analogy would lead us 

 to infer that they must communicate. 



The lobular arteries, " exceedinuly minute 

 and few in number," so as to be demonstrable 

 with much difficulty in the structure of the lo- 

 bules, enter the circumference of these bodies 

 with the lobular ducts upon which they are 

 distributed. They are the nutrient vessels of 

 the lobules, and terminate in the lobular venous 

 plexus formed by the portal vein. 



The mode of distribution of the hepatic ar- 



tery is a subject upon which some difference 

 of opinion subsists between Miiller and Kier- 

 nan. Kiernan states that the hepatic artery is 

 distributed chiefly upon the coats of the ducts 

 and gall-bladder, upon the coats of the other 

 vessels to which it forms the vasa vasorum, and 

 to the substance of the lobules. The ducts are 

 highly vascular, and are abundantly supplied, 

 the lobules sparingly, but " few" vessels, and 

 those " exceedingly minute," being traceable 

 into them. From the capillaries of the ducts 

 and vessels, the blood having become venous 

 during its circulation is returned into the portal 

 vein, and thence conveyed onwards to the lo- 

 bules, where it is distributed through the lobular 

 venous plexus. The blood of the terminal 

 lobular arteries also becomes venous in the 

 substance of the lobules, and is likewise poured 

 into the lobular venous plexus. So that, ac- 

 cording to this author, the whole of the blood 

 distributed through the hepatic artery is re- 

 ceived by the portal vein, either in the course 

 of that vessel, or at its termination in the lo- 

 bular venous plexus, and therefore, that all the 

 blood circulating through the plexus must ne- 

 cessarily be venous. He likewise affirms that 

 no part of the blood of the artery is poured 

 directly into the hepatic vein. "The intra- 

 lobular veins," he says, " convey the blood 

 from the lobular venous plexus, and not from 

 the arteries." These views are the results of 

 the evidence of numerous experimental injec- 

 tions. With regard to the vascularity of the 

 lobules, he observes, " These bodies cannot be 

 coloured with injection from the artery, even in 

 the young subject; in the adult, after the most 

 successful injection, when the arteries of the 

 cellular capsule, those of the excreting ducts 

 and gall-bladder, and the vasa vasorum are mi- 

 nutely injected, a few injected vessels only are 

 detected entering the lobules. I have fre- 

 quently tied the thoracic aorta in living animals, 

 thereby cutting off all supply of blood from 

 the abdominal viscera ; and in these animals, 

 when injected from the aorta below the ligature 

 forty-eight hours after death, the integuments, 

 the secreting portions of the kidneys, the spleen, 

 pancreas, intestines, and pelvic viscera were co- 

 loured in a remarkable degree by the injection ; 

 on the surface of the liver a few vessels only 

 could be discovered, this organ presenting a 

 curious contrast with the surrounding coloured 

 viscera. The gall-bladder and ducts were, how- 

 ever, equally well injected with the intestines ; 

 the vasa vasorum were also well injected." 

 Perceiving in the progress of his experiments 

 that the injection thrown into the artery passed 

 freely into the portal vein by means of the ca- 

 pillary communication existing between these 

 two vessels on the coats of the ducts, and 

 through the vasa vasorum of the vessels, he 

 imagined that the injected fluid might in this 

 way be diverted from the lobules, and that this 

 must be the cause of his want of success in 

 filling the lobular arteries. To ascertain if such 

 were the case, he injected the portal vein in the 

 first instance with blue, and then the arteries 

 with red. " On dissection, branches of the two 

 sets of vessels were found in the coats of the 



