In 1985, we first described a method for establishing primary cultures of nontransformed well differentiated hyperplastic biliary epithelium isolated in high purity and yield from the liver of bile duct-ligated rats (). Subsequently, numerous models for culturing biliary epithelial cell populations isolated from the livers of various experimental animal species, as well as the human, have been described. These include models of primary culture of intrahepatic biliary epithelial cells isolated from normal adult (-) and bile duct-ligated rats (,), from normal adult ( ) and bile duct-ligated mice (, ), from syrian golden hamster (), from guinea pig (), from pig (), from rainbow trout (), and from normal (, ) and diseased human livers (). Primary culture models have also been established for extrahepatic bile duct and gallbladder epithelial cells, respectively, isolated from both experimental animals and man (, , , , ). In addition, simian virus 40 (SV40) immortalized intrahepatic mouse () and human biliary () epithelial cell lines have been developed, which together with the establishment of a number of biliary cancer (cholangiocarcinoma) cell lines (), have each proven to be valuable in vitro systems for use in investigating important aspects of selected biliary functions and pathophysiology.