Histologic and scanning electron microscopic observations of intrahepatic peribiliary glands in normal human livers

The three-dimensional configuration of the intrahepatic peribiliary glandular system was examined in normal autopsied livers by scanning electron microscopic observations of the intrahepatic biliary tract casts. Biliary tract casts were made by injection of resin into the biliary tree and subsequent corrosion of the hepatic parenchyma. There were many projections on the surface of the biliary casts and they could be morphologically classified into pouchlike and treelike projections. These projections tended to be arranged on opposite sides of the biliary casts. The treelike projections from the large bile ducts at the bifurcation frequently anastomosed each other. By comparing the findings of biliary casts with histologic findings as well as the measuring of these projections and thickness of bile duct wall, it was suggested that the treelike projections correspond to the extramural peribiliary glands and the pouchlike ones to the intramural ones, both of which are normally present around the intrahepatic biliary tree. Thus, it was suggested stereologically in this study that substance(s) produced in the intrahepatic peribiliary glands may be secreted into the bile ductal lumen and thereby participate in the modification of bile composition.