Fig. 5. Endoderm-committed blastomeres and activated cells translocate directly to the YSL during gastrulation and develop an endodermal phenotype. Cells expressing GFP alone (A-D) or in combination with Tar* (E-H) or ECB (I-J) were transplanted to the animal pole of a host blastula. The group of grafted cells was monitored during development (lateral views). Until the beginning of gastrulation, grafted cells remain epiblastic (B,F,I), but during gastrulation, in contrast to control cells (C), Tar*-activated cells and ECB leave the epiblast to reach the surface of the YSL, without going through the margin (G,J). (D,H) Morphology of a single control and an activated grafted cell during gastrulation (70% epiboly). Note the filopodia characteristic of migrating endodermal cells in H (arrowheads).