Fig. 3. Endoderm-committed blastomeres and activated cells adopt an endodermal identity at the onset of gastrulation. During gastrulation (60% epiboly), endoderm-committed blastomeres (ECB) (A) or activated cells (C,D) transplanted to the animal pole (arrowheads) already express the endodermal genes sox17 and her5. Control cells do not (B). (B-D) Insets show close-up views of the region containing grafted cells.