Biliary epithelium: a new chapter in cell biology.

The intrahepatic biliary epithelium lines the biliary tree from the duct of Hering to the extrahepatic bile ducts. Until the early '90's, the biliary tree was considered to play only a mechanic role in transporting bile into the duodenum. In the last few years, a number of experimental models have generated a bulk of new knowledge showing how the biliary epithelium displays extraordinary properties in term of secretion, absorption, proliferation and signalling toward the other liver parenchymal and mesenchymal cells. It is now clearly emerging that the functions of biliary epithelium are tightly regulated by a number of hormones and neuropeptities. This heralds a number of nonvelities not only from a physiolgic point of view but also in terms of pathology and pharmacological management of the diseases targeting the intrahepatic biliary epithelium. The aim of this manuscript is to revise recent knowledge on cell biology of the biliary epithelium.