Liver Anatomy and Histology Arlin Rogers Comparative Pathology Laboratory Division of Comparative Medicine Comparative liver macroanatomy Human Lobes Right left caudate quadrate Majority of liver on R side cranial abdomen Subdivided into 9 discrete units based on vasculoductular supply important in surgery Rodent Lobes Right left median caudate More evenly spaced across cranial abdomen Rats lack gallbladder Gross anatomy View from above View from below Source Gray s Anatomy 1918 via Wikipedia This image has been released into the public domain by the copyright holder its copyright has expired or it is ineligible for copyright This applies worldwide Surgical segments Perfused rat liver image courtesy of CM North Michigan State University Source Wikipedia Lobe Couinaud segments Caudate 1 Left 2 3 Quadrate 4 Right 5 6 7 8 Several diagrams of liver structure removed for copyright reasons Vertical and horiztonal section anterior and interior surfaces and a detail cutaway showing interior ducts Mouse liver lobes Images removed for copyright reasons Source Figures 2 and 3 in Harada T et al Liver and Gallbladder Chapter 7 in Pathology of the Mouse Edited by Robert Maronpot Vienna IL Cache River Press 1999 ISBN 188989902X Liver functional unit classification schemes Lobule first described by Weppler 1665 Functional anatomy still not fully known Three main models Classical lobule Rappaport s acinus model Matsumoto s primary lobule Classical lobule Central vein peripheral portal triads Roughly hexagonal outline Blood flows from portal triads to central vein Species differences Pigs have well outlined lobules due to portal fibrous connective tissue many anatomy studies done with this species as a result Humans and nonhuman primates have discernible lobules Mice have poorly visualized lobules Two photos removed for copyright reasons Fig 10 74 and 10 75 from unknown source Lobule reticulin stain Figure removed for copyright reasons Source Figure 1 33 in MacSween MacSween R et al Pathology of the Liver 4th ed Philadelphia PA Elsevier 2002 Lobular division Figure removed for copyright reasons Source Figure 1 4 in MacSween Hepatic acinus Rappaport 1950 s Portal tracts are headwater elliptical zones spread to terminal hepatic central vein Zone 1 Periportal high enzyme O2 Zone 2 Intermediate Zone 3 Perivenular low O2 most susceptible to hypoxic injury Simple complex acini in berry like bunches Classical lobule vs acini Figure removed for copyright reasons Source Figure 1 7 in MacSween Comparison of Lobular and Acinar Terminologies Lobular Acinar Central centrilobular centrizonal Perivenular acinar zone 3 Mid zonal Acinar zone 2 Peripheral periportal Periportal acinar zone 1 Multilobular Multiacinar Panlobular Panacinar Central central necrosis or bridging Peri acinar complex necrosis or bridging Central portal necrosis or bridging Peri acinar simple peripheral acinar zone 3 necrosis or bridging Portal portal necrosis or bridging Portal portal necrosis or bridging Figure by MIT OCW Matsumoto s Primary Lobule Similar to classical lobule but incorporates current knowledge of vascular supply Sickle zone of complex periportal branching Otherwise a hybrid of classical acinar models Figure removed for copyright reasons Source Figure 1 9 in MacSween Primary vs classical lobule vascular network models Matsumoto Primary Lobule Figures removed for copyright reasons Source Figures 1 10 1 12 in MacSween Classical Lobule Arteriovenous connections in adult liver Figure removed for copyright reasons Source Figure 1 6 in MacSween Hepatic functional unit Kidney Nephron glomerulus to collecting duct Liver Not as well defined Choleon hepatocytes drained by a single canal of Herring Hepaton hepatocytes served by a single vascular twig Choleohepaton hybrid of above Hepatic microcirculatory subunit Figure removed for copyright reasons Source Figure 1 14 in MacSween Zonal heterogeneity Hepatocytes in different zones of lobule have different morphology gene expression and function O2 concentration Matrix proteoglycans Bile concentration Endothelial Kuffer cell adhesion molecules and cytokines Figure removed for copyright reasons Source Figure 1 5 in MacSween Biliary Tree Canaliculi Canals of Herring Bile ductules Intrahepatic bile ducts Extrahepatic bile ducts Gallbladder Common bile duct Canaliculi Interhepatocytic channels for bile flow 1 2 um diameter Bounded by zonula occludentes and zonulae and maculae adherentes Microfilaments in microvilli provide motility Bile flows opposite direction of blood Figures removed for copyright reasons Source Figure 1 23 1 24 Canal of Herring 1 39 Portal Triad and 1 26 in MacSween Gallbladder Sac for bile storage Empties into common bile duct under hormonal stimulation e g cholecystikinin Absent in rat and horse Image removed for copyright reasons Source Figure 9 in Harada T et al Liver and Gallbladder Chapter 7 in Pathology of the Mouse Edited by Robert Maronpot Vienna IL Cache River Press 1999 ISBN 188989902X Hepatic sinusoids 10 um diameter Fenestrated endothelium Space of Disse between endothelium and hepatocyte membrane exchange of molecules small frequent pores periportally sieve plate large pores centrilobularly pore size affected by hormones and alcohol Figure removed for copyright reasons Source Figure 1 31 in MacSween Resident Cells of the Liver Hepatocytes Biliary epithelium Endothelial Blood vessels Sinusoids Lymphatics Hepatic stellate Ito cells Kupffer cells resident M Liver associated lymphocytes Nerves connective tissue cells Hepatocytes 30 40 um polyhedral Polarized Apical canalicular region Lateral adjacent to canaliculi Basolateral facing sinusoids Endocrine and exocrine function Round open nuclei with dispersed and aggregated chromatin and prominent nucleoli Polyploidy is common increases with age Nuclear pore Schematic Drawing of the General Organization of a Cell Nuclear envelope Mitochondrion Granular vesicle secretory granule Basement membrane Golgi apparatus Granular endoplasmic reticulum Centriole Figure by MIT OCW Figure removed for copyright reasons Source Figure 1 1 in Cheville Cheville N F Ultrastructural Pathology An introduction to interpretation Ames IA Blackwell Publishing 1994 ISBN 0813823986 Hepatocyte organelles nucleus Large 5 10 of cell volume Double layered membrane with many pores Polyploidy humans Birth Nearly 100 diploid 8 years 90 diploid 15 years 85 diploid Cytoplasm doubles in volume for each nucleus maintaining steady ratio of genetic