Fig. 4. Frequency of endodermal markers rescue in MZoep by Cripto-injection at different times, displaying the frequencies corresponding to the four classes described in Fig. 3. Full rescue (Class I) was predominantly observed until sphere stage. Reduction of the number of endodermal cells expressing cas, sox17 or foxa2 was observed when Cripto protein was injected at dome (Classes II and III). At 40% epiboly, Cripto protein was not able to induce these markers in almost all injected embryos (Class IV). Embryos probed for foxa2 show that axial mesoderm but not endoderm was rescued when Cripto protein was injected at 40% epiboly (Fig. 3M).