Hepatocytes acinus

Han Nl, Lee YS, Choi H, Choi JY, Yun SK, Cho SH, Han JY, Yang JM, Ahn BM, Choi SW, Lee CD, Cha SB, Sun HS, Park DH (2002) PCNA expression and electron microscopic study of acinus-forming hepatocytes in chronic hepatitis B. Korean J Intern Med 17 100-106 Herve F, Urien S, Albengres E, Duche JC, TiUement IP (1994) Drug binding in plasma. A summary of recent trends in the study of drug and hormone binding. Qin Pharmacokinet 26 44-58... 

Figure 28.1. Comparison of structural liver lobule with functional acinar regions. The liver lobule is centered on the terminal hepatic venule (THV), also called the central vein, and assumes a roughly hexagonal shape with its vertices at the portal triads, which contain the portal vein (PV), hepatic artery (HA), and bile duct (BD). The liver acinus is centered upon the tract of blood vessels that branch from the hepatic artery and portal vein of the portal triads. Hepatocytes within the acinus are grouped within functional zones 1,2, and 3 located at increasing distances from the vascular tracts that interconnect adjacent portal triads.

Although the classic lobular model describes the microscopic appearance of the liver well, a better way to understand how the liver functions is to subdivide it into regions of hepatocytes irrigated by a single portal tract - an area referred to as the hepatic acinus. 

Blood emerging from the portal tract filters through the network of sinusoidal channels that separate rows of hepatocytes on its way towards the central vein. The hepatocytes within the acinus can be subdivided into three zones according to their distance from the portal venule. Cells in close proximity to the portal triad are the first to receive the nutrient- and oxygen-rich blood, and are consequently most... 

Hepatocytes display metabolic heterogeneity according to their zonal location within the acinus. (42) (s. p. 24) Specific chemical processes thus proceed exclusively or predominantly in the hepatocytes of the periportal or the perivenous zones. The zonally segregated reactions may also be regulated separately. It seems that, under certain conditions, metabolic processes are also shifted from one zone of the acinus to another. 

Tab. 3.2 Morphological heterogeneity of liver cells and organelles as well as metabolic heterogeneity of hepatocytes according to their respective zonal location in the acinus (s. pp 23, 24)...

There is considerable evidence that position within the acinus also affects important aspects of hepatocyte... 

The lobes of the liver are divided into smaller lobules with a roughly hexagonal arrangement of hepatocytes around a central vein. At the vertices of the lobules are bile ducts, terminal branches of the hepatic artery, and portal veins—termed the portal triad. Connective stromal tissues extend throughout the liver, providing support for cells and routes for blood vessels, lymphatic vessels, and bile ducts. The hepatocytes form groups of cells around small branches of the portal vein, hepatic arteriole, bile duct, lymph vessel, and nerves this functional unit is called an acinus (plural acini). The acini form part of a larger structure, which can be divided into three zones ... 

Cellular disruption leading to hepatocellular necrosis results from damage to cellular macromolecules by trichloromethyl radicals. Cellular disruption involves alteration of calcium homeostasis, " impaired oxidative phosphorylation, and trichloromethyl radical binding to cellular proteins, nucleic acids, and induction of lipid peroxidation. Histologically there is preferential necrosis of zone three hepatocytes in the liver acinus so called centrizonal necrosis as well as zone three steatosis. 

Gumucio, J. J. Miller, D. L. Krauss, M. D. ZanoUi, C. C. Transport of fluorescent compounds into hepatocytes and the resultant zonal lahehng of the hepatic acinus in the rat. Gastroenterology 1981,80, 639-646. 

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