Support for the liver progenitor cell hypothesis has come mainly from rodent models of
chemical hepatocarcinogenesis [1–5], from liver cell regeneration after chemical injury [6–8]
and from cell culture data (for review see ref.[9]). In these models, a periportal population of
small 'primitive'epithelial cells proliferates in association with or before hepatocyte
multiplication. These cells were called oval cells because of their shape [1, 2]. Oval cells are
related to terminal biliary ductules and the so-called canals of Hering [7, 10–13] and they …