THE VENA PORTJ3. 



471 



FIG. 166. 



887. When the Liver is closely examined with the naked eye, it is seen 

 to be made up of a great number of small granular bodies, about the size of 

 millet-seeds, of an irregular form, and presenting a number of rounded pro- 

 jecting processes upon their surfaces. These are commonly termed lobules, 

 although by some Anatomists they are spoken of as acini. 1 When divided 

 longitudinally, they have a somewhat foliated appearance (Fig. 166), arising 

 from the distribution of the Hepatic Vein, 

 which passes into the centre of each di- 

 vision. When transversely divided, the 

 lobules are usually found to present some- 

 what of a pentagonal or a hexagonal shape, 

 the angles being slightly rounded, so as to 

 form a seiiesof passages or interlobular 

 spaces: in these lie the branches of the 

 Vena Portte (as well as of the Hepatic 

 Artery and Duct), from which are derived 

 the plexuses that enter the lobules. The 

 exterior of each lobule is covered by a 

 process of the " capsule of Glisson," which 

 is very dense in the Pig and other animals, 

 but is so thin as to be almost (indistinguish- 

 able in the Human Liver ; the interspaces 

 between the vessels are filled by the ulti- 

 mate terminations of the Hepatic biliary ducts, which contain large secret- 

 ing cells. 2 The structure of each lob- 

 ule, then gives us the essential charac- 

 ters of the whole gland. 



388. The Vena Porte, which is 

 formed by the convergence of the veins 

 that return the blood from the chylo- 

 poietic viscera, probably also receives 

 the blood which is conveyed to the 

 liverforthe purposes of nutrition by the 

 Hepatic Artery. Like an artery, it 

 gradually subdivides into smaller and 

 yet smaller branches; and at last it 

 forms a plexus of vessels, which lie 

 in the interlobular spaces, and spread 

 with the freest inosculation through- 

 out the entire Liver. To these ves- 

 sels, the name of inferlobular Veins 

 was given by Mr. Kiernan. 3 They 

 ramify in the capsules of the lobules, 

 covering with their ramifications the 

 whole external surface of these ; and 

 then enter their substance. When 

 they enter the lobules, they are termed 

 lobular veins; and the plexus formed by their convergence from the cir- 



Connection of the Lobules of the Liver 

 with the Hepatic Vein : 1, trunk of the Vein: 

 2, 2, 2, lobules depending from its branches, 

 like leaves on a tree; the centre of each 

 beins; occupied by a venous twig, the Ir.tra- 

 lobular Vein. 



FIG. 167. 



Horizontal section of three superficial Lobules, 

 showing the two principal systems of Bloodves- 

 sels: 1, 1, i/ifralobular veins, terminating in the 

 Hepatic veins; 2, 2, iw/erlobular plexus, formed 

 by branches of the Portal vein. 



Malpiglii are the minute bodies of various forms and yellowish color, 

 which are seen when any individual lobule is examined with the microscope; these 

 are nothing else, however, than the irregular islets of parenchyma, left between the 

 meshes of the plexus formed by the ultimate ramifications of the portal vein. 



2 See Prof. Beale's paper, On the Ultimate Arrangement of the Biliary Ducts, in 

 Phil Trans., 18o6, and Todd and Bowman's Physiolog. Anat., p. 459, vol. ii, 1859. 



3 See his admirable Memoir, On the Anatomy and Physiology of the Liver, in the 

 Philosophical Transactions, 1833. 



