[Embryonic stem cells: from fundamental studies--to clinical application]

A short history of embryonic stem cell (ESC) discovery, cell line isolation, phenotyping and cell behavior both in situ and in vitro is outlined. The path of ESC differentiation into restricted specialized cell types mediated by signal network in culture and by grafting cell into recipient tissues is considered. Potentialities of ESC as the generator of spare parts of organs for regenerative medicine and related bioethical issues are briefly outlined.