- Normal LiverNalini Bansal Gupta, Apurba Rajbongshi
- Important Aspects of Liver BiopsyNalini Bansal Gupta
- Simple Approach to Liver Biopsy InterpretationNalini Bansal Gupta, Chhagan Bihari
- Special Stains and ImmunohistochemistryKaushik Majumdar, Puja Sakhuja
- Acute or Chronic Liver Failure and Clinical ScoresNalini Bansal Gupta
Liver has grossly four lobes (Figs 1A and B):
- Right lobe—largest
- Left lobe
- Caudate lobe—drains directly into inferior vena cava
- Quadrate lobe.
For surgical resections liver is divided into eight segments (Fig. 2) by Couinaud system with each lobe having independent vascular pedicle (portal venous, arterial and lymphatic branches) and biliary drainage facilitating easy surgical segmental resection.1,2
Liver on histology has hexagonal lobules described by Kiernan in 18333 comprising of portal tracts constituting the periphery of the hexagonal lobule, occupying three of the six apices of the hexagon (Fig. 3). The effluent hepatic vein is at the center of the lobule, hence its name central vein.4
Normal liver biopsy shows:
- Hepatocytes arranged in plates (liver cell plates)
- Central vein
- Portal tract showing triad of hepatic artery, bile duct, portal vein.
- Constitute 80% of all cells in normal liver
- Hepatocyte—polygonal cell with a small round nucleus and abundant pink finely granular cytoplasm due to abundant glycogen contents and mitochondria. Binucleate forms can be seen
- Hepatocytes are aligned in uniform single cell plate arrangement from central vein to portal tract (Fig. 4)
- In children up to 5–6 years of age, hepatocyte plate can be two cells thick
- They directly abutt on central vein with no significant connective tissue between them.
Hepatocytes contain following organelles:
- Golgi complexes
- Rough/smooth endoplasmic reticulum.
Hepatocytes are polygonal cells and have three domains/surfaces.
- Basolateral Domain/Vascular Pole/Sinusoidal
- 35% of hepatocyte surface faces sinusoids and perisinusoidal space of Disse (SOD)
- It has microvilli that protrude into sinusoids and maintain integrity of SOD
- It has N-K ATPase pump, NTCP (Sodium taurocholate cotransporting peptide) and OATP (Organic anion transporting polypeptide C). NTCP involved in sodium dependent uptake of bile acid from sinusoids.
- Apical/Canalicular DomainIt comprises 15% of hepatocyte surfaces and faces bile canaliculi. It has several ATP dependent export pumps belonging to ATP binding casette (ABC). Their main function is bile secretion in canaliculi.ABC include following transporters:
- Bile salt export pump (BSEP) transport bile salt into bile canaliculi
- Multidrug resistant protein 3 (MDR3)—is a phospholipid transporter, translocates phosphatidylcholine from inner to outer membrane of hepatocyte and release it into bile canaliculi which is then taken up by bile salts
- Multidrug resistance-associated protein 2 (MRP2)—transport glutathione into bile.
- Lateral Domain50% of total hepatocyte surface faces adjacent hepatocytes.
Hepatocyte Paraffin 1 (Hep Par 1): It is antibody against urea cycle enzyme (carbamoyl phosphate synthetase 1) present in mitochondria and take fine granular cytoplasmic stain. It is useful for identifying hepatocyte differentiation.
HEPATOCYTE COUPLET (FIG. 5)
- It is a model for studying bile physiology
- It comprises of two adjacent hepatocyte with a bile canaliculus in between.
ZONATION (FIGS 6A AND B)
For better understanding of liver histological and metabolic perspective, liver lobule is divided into three zones.
- Zone 1: Periportal
- Nearest to the incoming vascular supply and receives the most oxygenated blood
- Least sensitive to ischemic injury while making it very susceptible to chronic viral hepatitis, toxins and heavy metals injury7
- Specialized for oxidative liver functions, such as gluconeogenesis, β-oxidation of fatty acids, urea cycle functions and cholesterol synthesis.
- Zone 2: Midzonal
- Zone 3: Perivenular
- Is least oxygenated
- Most commonly affected during ischemic injury
- Zone III cells are more important for glycolysis, lipogenesis and cytochrome P-450-based drug detoxification and rich for glutamine synthetase.8
Zonal Heterogeneity in the Liver9
As different zones of liver perform different function there is zonal heterogeneity in the liver (Fig. 7).
Two type of heterogeneity are seen:
- Gradient Zonation: Present in all zones but expression differs—In the gradient type, all hepatocytes are able to express a particular gene, but the level of expression depends on the position of the hepatocyte along the portocentral radius like enzymes of carbohydrate metabolism, cytosolic phosphoenol-pyruvate carboxykinase I (PCK) and glucokinase
- Compartment Zonation: Present only in specific zones: In the compartment type of zonation, the expression of genes has been thought to be restricted to either the periportal or the pericentral compartment, e.g. key enzymes of ammonia metabolism, carbamoyl phosphate synthetase I (CPS) and glutamine synthetase (GS), which in normal liver exhibit strict localization to hepatocytes rimming the terminal hepatic vein.
SPACE OF DISSE
- Very important space as it contains vital cells of liver pathology
- The space of Disse (SOD) was named after German anatomist Joseph Disse10
- It is fluid space between basolateral domain of hepatocyte and sinusoidal endothelial cells (Fig. 8)
- Also known as perisinusoidal extravascular space.
Components of SOD
It has four different cell types and extracellular matrix (ECM). Four cell types in SOD are:
- Hepatic stellate cells (HSC)
- Sinosoidal endothelial cells
- Kupffer cells
- Liver-associated lymphocytes/pit cells (NKT cells).
- Zone 3/perivenular—ECM comprises of fibronectin, type III collagen and dermatan sulphate.
Hepatic Stellate Cells (HSC)
- First described by von Kupffer as ‘Sternzellen’ or star cells13
- Toshito Ito named them as fat storing cells/Ito cells14
- Named as perisinusoidal cells containing vitamin A by Kenjiro Wake15
- Store 80% of retinoids in the whole body as retinyl palmitate in lipid droplets in the cytoplasm
- Play pivotal roles in the regulation of retinoid homeostasis; they express specific receptors for retinol-binding protein (RBP) on their cell surface, and take up the complex of retinol and RBP by receptor-mediated endocytosis
- Regulate sinusoidal blood flow
- Important regulators for regeneration and controlling the process of regeneration
- It helps in neoangiogenesis and myofibroblast migration
- They are also involved in epithelial mesenchymal transition (EMT) during liver injury.
Sinusoidal Endothelial Cells (SEC)
- Discontinuous fenestrated endothelial cells
- It known as sinusoidal as they have no basement membrane and form a fenestrated lining
- Diameter of fenestrae is 150–175 nm
- Fenestrate are more in zone 3/perivenular region than in zone 1 as zone 3 receives relatively less oxygenated blood23
- They are different from endothelial cells lining glomerular capillaries in kidney by absence of basement membrane.26
- There are two subgroup of liver macrophages—resident macrophages also known as Kupffer cells and infiltrating macrophages.
- Liver macrophages derived from monocytes—mononuclear group of macrophages27
- Located within the lumen of sinusoids
- Most numerous in the portal regions28
- When activated → produce large amounts of chemokines/cytokines
- Acute liver inflammation begins with activation of Kupffer cells.
- 65% lymphocytes in liver are NK cells expressing TCR and remaining are T and B cells (minority)
- NKT cells also known as Pit cells are large granular lymphocytes in subendothelial layers in space of Disse
Portal Tract (Fig. 9)
- Comprises of hepatic artery, bile duct and portal vein
- Hepatic artery and bile duct are of same caliber
- Portal vein has the largest caliber
- Portal mesenchyme
- Normal ratio of bile duct to portal tract 0.9–1.8
- Limiting plate—discontinuous lining of hepatocytes around the portal tract
- Periportal hepatocytes—Hepatocytes adjacent to limiting plate are called periportal hepatocytes.
Space of Mall
Fluid space between hepatocytes along the limiting plate in the periportal area, and portal tract fibrous tissue; it is in continuity with the perisinusoidal space of Disse.
Are present between the hepatocyte plates. Through the sinusoids blood comes from portal tract through hepatic artery and portal vein and drains into central vein. Periportal region thus receives more oxygenated blood as is near to portal tract.
- Terminal hepatic venule (THV), also known as central vein, is the smallest tributary of hepatic vein. It collects venous blood draining through sinusoids of a hepatic lobule (Fig. 10).
- It joins with similar veins of other lobules and forms the main hepatic vein.
Billiary system comprises of bile canaliculi which collect bile from hepatocytes and near portal interface → Canaliculi drain into canals of Hering (lined partly by hepatocytes and partly by cholangiocytes) → Canal of Hering drains into bile ductules (or Cholangioles) which begin at the limiting plate (interface bertween parenchyma and portal tract) → Medium-sized interlobular ducts → Septal ducts → Area ducts → Segmental ducts → Left and right hepatic ducts. Intrahepatic biliary duct system (IHBD) comprises of large duct including area, segmental and right and left hepatic duct which also form main hepatic ducts intrahepatic biliary ductal system (Table 1).31
Larger ducts are lined by peribiliary mucous glands which are of two types:
- Intramural—Directly draining in duct lumen
- Extramural—Drain through secretory duct.
- Cholangiocytes are flattened or cuboidal in small branches of biliary tree
- Columnar in large branches
- Mounts IgA and IgM response (not IgG)
- Capable of proliferating after liver injury.
- Canalicular network can be highlighted with immunostains for PCEA, CD 10, MDR3 and MUC1
- Polyclonal carcino embryonic antigen (pCEA)—Antibody react and stains a CEA like cross reactive substance called biliary glycoprotein present in bile canaliculi and ductal epithelium but not hepatocytes (Fig. 11).
Where can we get normal Biopsy
Received mainly from perspective liver donors for assessment of steatosis, inflammation or significant fibrosis.
LIVER BIOPSY SIGN OUT FOR NORMAL BIOPSY
No significant inflammation/fibrosis/steatosis seen.
- Couinaud C. Le foie; études anatomiques et chirurgicales. Paris: Masson et Cie; 1957.
- Ger R. Surgical anatomy of the hepatic venous system. Clin Anat. 1988;1:15–22.
- Kiernan F. The anatomy and physiology of the liver. Philos Trans R Soc Lond. 1833;123:711–70.
- Ekataksin W, Wake K. New concepts in biliary and vascular anatomy of the liver. In: Boyer JL, Ockner RK, editors. Progress in liver diseases. Vol. XV. Philadelphia: WB Saunders; 1997. p. 1–30.
- Schachter D. The hepatocyte plasma membrane: organisation and differentiation. In: Arias IM, Jakoby WB, Popper H, et al. editors. The liver: biology and pathobiology. New York: Raven Press; 1988. p. 131–40.
- Meier PJ. Transport polarity of hepatocytes. Semin Liver Dis. 1988;8:293–307.
- Bacon BR, O'Grady JG, Di Bisceglie AM, Lake JR. Comprehensive Clinical Hepatology. Elsevier Health Sciences; 2006.
- Schiff ER, Sorrell MF, Maddrey WC, ed. Schiff's Diseases of the Liver, 10th Edition. Lippincott William & Wilkins; 2007.
- Baier PK, Hempel S, Waldvogel B, Baumgartner U. Zonation of hepatic bile salt transporters. Dig Dis Sci. 2006;51:587–93.
- Haubrich WS et al. “Disse of the space of Disse”. Gastroenterology. 2004;127(6):1684.
- Reid LM, Fiorino AS, Sigal SH, et al. Extracellular matrix gradients in the space of Disse: relevance to liver biology. Hepatology. 1992;15:1198–203.
- Martinez-Hernandez A, Amenta PS. Morphology, localization and origin of the hepatic extracellular matrix. In: Sern M, Reid L, editors. Extracellular matrix: chemistry, biology, pathology. New York: Marcell Dekker; 1993.
- “Kupffer of Kupffer cells”. Gastroenterology. 127(1):16.
- “Professor Toshio Ito: A clairvoyant in pericyte biology”. The Keio Journal of Medicine. 50(2):66–71.
- Wake K. Perisinusoidal stellate cells (fat-storing cells, interstitial cells, lipocytes), their related structure in and around the liver sinusoids, and vitamin A—storing cells in extrahepatic organs. Int Rev Cytol. 1980;66:303–53.
- Burt AD, Robertson JH, Hair J, MacSween RNM. Desmin-containing stellate cells in rat liver; distribution in normal animals and response to experimental acute liver injury. J Pathol. 1986;150:29–35.
- Schmitt Graff A, Kruger S, Bochard F, et al. Modulation of alpha smooth muscle actin and desmin expression in perisinusoidal cells of normal and diseased human livers. Am J Pathol. 1991;138:1233–42.
- Senoo H. Structure and function of hepatic stellate cells. Med Electron Microsc. 2004;37:3–15.
- Balabaud C, Biolac-Sage P, Demouliere A. The role of hepatic stellate cells in liver regeneration. J Hepatol. 2004;40:1023–6.
- Bachem MG, Schneider E, Gross H, et al. Identification, culture and characterization of pancreatic stellate cells in rats and humans. Gastroenterology. 1998;115:421–32.
- Friedman SL. Hepatic stellate cells: protean, multifunctional, and enigmatic cells of the liver. Physiol Rev. 2008;88:125–72.
- McGuire RF, Bissell DM, Boyles J, Roll FJ. Role of extracellular matrix in regulating fenestrations of sinusoidal endothelial cells isolated from normal rat liver. Hepatology. 1992;15:989–97.
- Petrovic LM, Burroughs A, Scheuer PJ. Hepatic sinusoidal endothelium: Ulex lectin binding. Histopathology. 1989;14:233.
- Scoazec J-Y, Feldmann G. In situ phenotyping study of endothelial cells of the human hepatic sinusoid: results and functional implications. Hepatology. 1991;14:789–97.
- Elvevold K, Smedsrød B, Martinez I. The liver sinusoidal endothelial cell: A cell type of controversial and confusing identity. Am J Physiol. 2008;294:391–400.
- Winwood PJ, Arthur MJP. Kupffer cells: their activation and role in animal models of liver injury and human liver disease. Semin Liv Dis. 1993;13:50–9.
- Wake K, Decker K, Kirn A, et al. Cell biology and kinetics of Kupffer cells in the liver. Int Rev Cytol. 1990;118:173–229.
- Norris S, Collins C, Doherty DG, et al. Resident human hepatic lymphocytes are phenotypically different from circulating lymphocytes. J Hepatol. 1998;28:84–90.
- Shimizu Y, Iwatsuki S, Herberman RB, Whiteside TL. Clonal analysis of tumor-infiltrating lymphocytes from human primary and metastatic liver tumors. Int J Cancer. 1990;46:878–83.
- Desmet VJ, Roskams T, De Vos R. Normal anatomy in gallbladder and bile ducts. In: LaRusso N, editor. Gastroenterology and Hepatology: The comprehensive visual reference current medicine. Vol 6 Philadelphia; 1997; pp. 1–29.
- Glaser SS, Gaudio E, Miller T, et al. Cholangiocyte proliferation and liver fibrosis. Expert Rev Mol Med. 2009;11:e7. Review.
- Ros JE, Libbrecht L, Geuken M, et al. High expression of MDR1, MRP1, and MRP3 in the hepatic progenitor cell compartment and hepatocytes in severe human liver disease. J Pathol. 2003;200:553–60.
- Baiocchi L, Le Sage G, Glaser S, Alpini G. Regulation of cholangiocyte bile secretion. J Hepatol. 1999;31:179–91.