Fig. 6. Isolation of mesendoderm cells and endoderm cells from genetically unmanipulated ES cells. (A) Purification of ECD⁺R⁺ mesendoderm cells. EB5 unmodified ES cells were cultured in SFM containing activin. On day 4, ECD⁺R⁺ cells were purified by FACS and re-cultured for 2 days. Both ECD^- and ECD⁺ populations (labelled A and B, respectively) derived from day 4 ECD⁺R⁺ cells were sorted again by FACS for further analyses. (B) The expression of mesoderm and endoderm markers in ECD^- and ECD⁺ populations (labelled A and B, respectively). A set of endoderm markers such as Foxa2 and Sox17 was exclusively expressed in B, whereas the expression of mesoderm markers such as ßR and Vegfr2 was detected only in A. (C) The morphology of endoderm cell line derived from wild-type ES cells. Epithelial-like morphology with clear cell-cell boundary is present. This morphology is similar to endoderm cell lines generated from Gsc⁺ECD⁺ cells (Fig. 4B).