MONOLAYER-CULTURE CONDITIONS SUITABLE FOR PRIMITIVE ERYTHROID CELL-DIFFERENTIATION FROM EMBRYONIC STEM-CELLS IN-VITRO

Embryonic stem (ES) cells effectively differentiated into primitive er ythroid/mesodermal cells when grown in the absence of both a feeder la yer and leukemia inhibitory factor (LIF). The formation of a three-dim ensional structure, exogenous mesoderm induction factors and exogenous hematopoietic growth factors were not essential for their differentia tion. Primitive erythroid cells were first detected on day 5 in the di fferentiation-permissive cultures. Differentiation into other mesoderm al cells was always preceded by that into primitive erythroid cells. P recursor cells of erythroid cells but of other hematoid cells were als o detected in this system. This model system is useful for studying th e early steps of mesoderm formation in mouse embryogenesis.