Abstract: Embryonic stem cells （ESC），derived from the inner cell mass，is a highly undifferentiated cells with unlimited proliferation and developmental totipotency. ESC can spontaneously differentiate into many cell types，such as neurocytes，pancreatic cells，cardiocytes，and so on. Previously，ESC were mainly induced to differentiate into a variety of cells by forming the embryoid body （EB），but the efficiency was low. New studies showed that ESC can directly differentiate into definitive endoderm and further into hepatocytes by simply adding inducible factors，by which the efficiency was greatly improved. The efficiency of induced differentiation can be evaluated by the surface markers of definitive endoderm，such as SOX17 and FOX2. However，it is not very clear what combination of inducing factors has the highest efficiency and is closest to the normal development of human embryo.

Key words: Embryonic stem cells, Embryo, mammalian, Cell line, Endoderm, Hepatocytes