Figure 2: Sections of chick embryos 48 hours post grafting. The embryos were stained by whole-mount immunofluorescence followed by microtome sectioning. Activin A-induced putative DE derived from hESC (A-B) or mESCs (C-D) integrate in the chick endoderm after grafting, whereas hESC progeny (E-F) or mESC progeny (G-H) not treated with Activin A are rarely found in the developing endoderm. (I-L) Grafted Sox17+ mDE integrates in the chick endoderm and can participate in the development of the Nkx6-1+ chick pancreatic endoderm. The GFP signal from the Sox17+ cells is quenched during the whole mount staining procedure, which permit the detection of Nkx6-1 in the green channel. The arrowhead points at site of integration. CMTMR= CellTracker™ Orange dye, FP= Floor plate, E= Endoderm, NT= Neural tube.