A substantially enriched mammalian hepatic liver engrafting cell population is provided. Methods are provided for the isolation and culture of this liver engrafting cell. The progenitor cells are obtained from a variety of sources, including fetal and adult tissues. The cells are useful in transplantation, for experimental evaluation, and as a source of lineage and cell specific products, including mRNA species useful in identifying genes specifically expressed in these cells, and as targets for the discovery of factors or molecules that can affect them.