The germ-cell lineage in mammals is believed to separate from somatic lineages around the time of gastrulation. We present data showing that germline cells can originate from a human hepatic cell line (HL7702) in vitro. In specific culture conditions, the HL7702 cells gave rise to a subpopulation of morphologically distinct cells, some of which expressed germline-specific markers, consistent with germ cell formation. After prolonged culture, the putative germ cells were capable of forming follicle-like structures, generating oocyte-like cells, subsequently developing into blastocyst-like structures in vitro, and causing germ cell/embryonic tumors in vivo, thereby indicating that the human hepatic cells actually have the potential of germline cells in vitro. Our findings will provide a novel way to obtain human germ cells and a new model to investigate human oogenesis in vitro.