Fig. 336. acini, to which allusion has been made, are termed by him lobules. Fig. 335, 1, exhibits some of the cells of which the lobules are composed, seen under a magnifying power of 200 diameters. 2, represents a longitudinal section of a lobule with ramifications of the hepatic vein: and Fig. 336, the connexion of the lobules with the same vein; -the centre of each being occupied by a venous twig-or intralobular vein. Fig. 337 represents the lobules as seen on the surface of the liver when divided transversely. In this, 2, exhibits the interlobular spaces; 3, interlobular fissures; 4, intralobular veins occupying Connexion of Lobules of Liver with Hethe centres of the lobules; and 5, smaller veins terminating in the central containing an intralobular or hepatic twig. veins. Fig. 338, is a similar section of three lobules, showing the arrangement of the two principal systems of blood vessels; 1, 1, intralobular veins; and 2, 2, interlobular plexus Fig. 337. patic Vein. 1. Hepatic vein. 2, 2, 2. Lobules, each Fig. 338. formed by branches of the vena porta. Fig. 339 represents a horizontal section of two superficial lobules, showing the interlobular plexus of biliary ducts: 1, 1, intralobular veins; 2, 2, trunks of biliary ducts, proceeding from the plexus, which traverses the lobules; 3, interlobular tissue; and 4, parenchyma of the lobules. The interlobular biliary ducts ramify upon the capsular surface of the lobules; and then enter their substance and are supposed to subdivide into minute branches, which by anastomoses with each other form the reticulated plexus depicted in Fig. 339, called by Mr. Kiernan the lobular biliary plexus. It is from this arrangement of the blood vessels and biliary ducts, that Mr. Kiernan infers that bile must be secreted from the portal VOL. II.-20 Fig. 339. vessels; the intralobular ramifications of the hepatic veins conveying back to the heart the blood which has been inservient to the secretion. The views of Mr. Kiernan have been generally adopted by anatomists. Wagner, however, whilst he regards the beautiful figures and descriptions of Mr. Kiernan as the best he has seen, asserts, Horizontal Section of two Superficial Lobules, that they very certainly also showing Interlobular Plexus of Biliary Ducts. include many mistakes; whilst Krause "combats the views of Kiernan, holding them to be hypothetical;" and E. H. Weber and Kronenberg oppose them. The chief point, according to Mr. Paget, in which these gentlemen differ from Mr. Kiernan, is in denying that the component parts of the liver are arranged in lobules. They, with Henle and Mr. Bowman, describe the capillary networks as solid,-that is as extending uniformly through the liver. They, also, deny the existence of fibrocellular partitions dividing the liver into lobules as maintained by Mr. Kiernan and J. Müller; and even the existence of more fibro-areolar tissue than serves to invest the larger vessels, &c., of the organ. They Fig. 340. Fig. 341. likewise deny that there are any such interlobular veins and fissures as Mr. Kiernan describes, and state, that the smaller branches of these veins communicate by branches only just larger, if at all larger, than capillaries." I Wagner, Elements of Physiology, by R. Willis, § 195, Lond., 1842. 2 Müller's Archiv., 1844, Heft 3. 3 Ibid. • Ibid. 5 See, on all this subject, Professor Theile, art. Leber, Wagner's Handwörterbuch der Physiologie, 9te Lieferung, s. 308, Braunschweig, 1845. Fig. 342. Histologically considered, the liver may be regarded as consisting of ramifications of excretory ducts, surrounded by blood vessels, which afford the materials for secretion, and of cells which elaborate it, but as respects the precise arrangement of the cells anatomists are not wholly in accordance. Dr. Leidy' affirms, that they line the inner surface of the tubuli that form the biliary plexus of Kiernan; that they are irregularly angular or of a polygonal shape, owing to their pressing upon each other; and contain a fine granular matter, oil globules, a granular nucleus and transparent nucleolus,-the oil globules, under special circumstances of diet and disease, experiencing considerable increase. Dr. C. Handfield Jones' has, however, recently maintained, that the ramifications of the hepatic ducts do not enter the lobules as maintained by Mr. Kiernan, but are confined to the inter- Hepatic lobular spaces, the substance of the lobules being composed of secreting parenchyma and blood vessels; and that the action of the liver seems to consist in the transmission of the bile, as it is formed, from cell to cell, until Fig. 343. Cells gorged with Fat. a. Atrophied nucleus. b. Adipose globules. Minute Portal and Hepatic Veins and Capillaries. a, a. Twigs of the portal vein. d. Twig of the hepatic vein. b. Intermediate capillaries. it arrives in the neighbourhood of the excretory ducts by which it is absorbed. Perhaps the best mode, according to Br. Budd,' to get a general 1 American Journal of the Medical Sciences, p. 1, Jan., 1848; and Quain's edition of Quain and Sharpey's Human Anatomy, ii. 487, Philad., 1849. 2 Philosophical Transactions, Pt. i., for 1849. 3 On Diseases of the Liver, Amer. edit., p. 17, Philad., 1846. idea of the structure of the liver is to examine under the microscope, -first, a thin slice of liver, in which the portal and hepatic veins are thoroughly injected; and secondly,-a small particle taken from the lobular substance of a fresh liver, in which the blood vessels are empty, as in an animal killed by bleeding. Figure 343, from a specimen by Mr. Bowman, represents, on a magnified scale, a small branch of the hepatic vein, two or three branches of the portal vein, and the intermediate capillaries. The capillaries appear to have nearly the same relation to the branches of the portal vein as they have to those of the hepatic. It is difficult to tell, from this specimen, which branch is portal and which hepatic,-the smaller branches of both being, as it were, hairy with capillaries springing directly from them on every side, and forming a close and continuous network. Dr. Budd thinks, that the injected preparations of Mr. Bowman show clearly, that the opinion of Malpighi, Kiernan, Müller, and others, that the lobules are isolated from each other, each being invested by a layer of areolar tissue, is erroneous; and that the lobules are not dis a, a, a. Minute twigs of the portal vein. b, b, b. Capillaries immediately springing from them, and serving with them to mark the outline of the lobules. d, d, d. Capillaries in the centre of the lobules, injected through the hepatic vein. e, e. Places at which the size injected into the portal vein has met that injected into the hepatic vein, so that all the intermediate capillaries are coloured and conspicuous. 1, 1. Centres of lobules into which the injection has not passed through the hepatic vein. tinct, isolated bodies, but merely small masses, tolerably defined by the ultimate twigs of the portal vein, and the injected or uninjected capillaries immediately contiguous to them. The lobules, according to Dr. Budd, appear only as distinct isolated bodies when seen by too low a magnifying power to clearly distinguish the capillaries. The real nature of the lobules, and the manner in which they are formed, will perhaps be better understood, he thinks, by reference to the illustration, (Fig. 344,) for which he expresses his indebtedness to Mr. Bowman. It represents, on a magnified scale, six lobules of the liver, and was made from a drawing under the microscope of a section of the liver of a cat, partially injected through the portal vein, and also through the hepatic. Mr. Kiernan has deduced interesting pathological inferences from the anatomical arrangement of the liver which he conceives to exist; A B (Kiernan.) thus, he considers that the lobules Portal Venous Congestion. B. Interlobular spaces and fissures. C. Intralobular veins. D. Anæmic portions. E. Con 1 Practice of Medicine, 3d edit., vol. ii. chap. 3, Philad., 1848. |