The intrahepatic biliary passages of a teleost liver composed by a muralium duplex was studied by electron microscopy. The bile canaliculus was commonly formed by 2 or more hepatic cells. In the transition zone between the intercellular bile canaliculus and the bile ductule, this duct was formed in part by hepatic cells and in part by duct cells. While the number of duct cells increased, the number of hepatocytes decreased until the entire ductule was formed by 2 or 3 duct cells. Bile duct was formed only by pyramidal duct cells. These cells are readily distinguished from the hepatocytes by its irregular shape, by a paucity of organelles and by the abundance of microfilaments.