Intrahepatic Bile Ducts (Hepatic Biliary Radicals): Anatomy and Function

The term "hepatic biliary radicals" refers to the intrahepatic bile ducts—the branching ductules within the liver that collect bile from hepatocytes.

Anatomy

1. Bile canaliculi: Tiny channels between adjacent hepatocytes (no basement membrane).
2. Canals of Hering: Transition zone connecting canaliculi to ductules; stem cell niche.
3. Bile ductules (cholangioles): Lined by cuboidal cholangiocytes; <15 µm diameter.
4. Interlobular ducts: Connective tissue wall; accompany portal triads.
5. Septal/segmental ducts → right/left hepatic ducts → common hepatic duct.

Function

• Transport bile (bile acids, bilirubin, cholesterol, phospholipids, proteins) from hepatocytes to duodenum.
• Cholangiocytes modify bile: secrete HCO₃⁻, water (secretin-stimulated); reabsorb glucose, amino acids.
• Concentrate bile during fasting (gallbladder stores; sphincter of Oddi regulates release).

Clinical Relevance

• Cholangiocarcinoma arises from cholangiocytes (intrahepatic, perihilar, distal).
• Primary sclerosing cholangitis (PSC): inflammatory stricturing of intra/extrahepatic ducts.
• Caroli disease: congenital dilation of intrahepatic ducts.
• Obstruction → cholestasis → jaundice, pruritus, malabsorption, cirrhosis.

Intrahepatic ducts are unequivocally within the liver parenchyma.