Bile canaliculi are small, tubular channels found within the liver that play a critical role in the transport of bile. They are formed by the tight junctions between the apical (canalicular) membranes of adjacent hepatocytes, which are the main parenchymal cells of the liver.

Bile is a fluid produced by hepatocytes that contains bile salts, bilirubin, cholesterol, phospholipids, and other waste products. Bile has several important functions, including the emulsification and absorption of dietary fats and fat-soluble vitamins, the elimination of waste products (such as bilirubin and excess cholesterol), and the regulation of intestinal pH.

The bile canaliculi serve as the initial pathway for bile transport, where it flows from the hepatocytes towards the bile ducts. The bile canaliculi merge to form progressively larger bile ductules, which eventually join to create the larger hepatic ducts. These hepatic ducts then combine to form the common hepatic duct, which carries bile out of the liver and into the gallbladder for storage or directly into the small intestine for digestion.

The movement of bile through the bile canaliculi is facilitated by the coordinated contraction of hepatocytes and the action of bile salt export pumps located on the apical membrane of hepatocytes. These pumps actively transport bile salts and other organic anions into the canaliculi, creating an osmotic gradient that drives the movement of water and other components of bile.

Impaired bile flow, or cholestasis, can occur due to various factors, such as bile duct obstruction, liver disease, or genetic disorders. Cholestasis can lead to the accumulation of toxic substances in the liver, causing liver damage, jaundice (yellowing of the skin and eyes), and other complications. Treatment for cholestasis depends on the underlying cause and may include medications, surgical intervention, or liver transplantation in severe cases.