Mouse epiblast stem cells (EpiSCs) provide a platform for studying mammalian postimplantation development in vitro.Mouse embryonic stem cell (mESC) is a heterogeneity and plasticity pluripotent populations.However,it remains unclear whether EpiSCs have this property.EpiSCs is the most proximal pluripotent cell line to the early somatic and germ precursors.Little is known about the differention potential of subpopulation of EpiSC in vitro corresponding to distinct mouse pre-gastrulation developmental states.Here.we show that EpiSCs comprise two distinct subpopulations which distinguished by the expression of a specific Brachyury(T)-GFP marker,and T-