biliarkanalikuli

Biliarkanalikuli, known in English as bile canaliculi, are microscopic channels that form the first functional units of the biliary tree within the liver. They are located in the hepatic lobules and arise from the apical surfaces of adjacent hepatocytes, creating a network through which bile produced by hepatocytes is collected and directed toward the larger biliary ducts via the canal of Hering and interlobular bile ducts in the portal tract.

Anatomically, bile canaliculi are bounded by tight junctions between neighboring hepatocytes, so the lumen is formed by the adjoining apical membranes. The canalicular surface often bears microvilli, increasing surface area for solute and fluid transport. Although they lack an independent epithelial lining, they function as continuous conduits that integrate with the surrounding cellular and vascular architecture of the liver.

Physiologically, canalicular bile formation involves transport proteins on the canalicular membrane. Key players include BSEP (bilir bile acid export pump), which moves bile acids into the canaliculi; MDR3, which translocates phospholipids into bile; and MRP2, which exports conjugated organic anions. These processes generate and regulate the composition and flow of bile toward the ducts that eventually carry bile out of the liver.

Clinically, dysfunction of canalicular secretion or obstruction of the downstream ducts can lead to intrahepatic cholestasis, with elevated bilirubin and alkaline phosphatase. Drug-induced cholestasis and certain developmental or obstructive disorders can impact canalicular transport or flow.

See also: hepatocytes, canal of Hering, bile ducts.