Fig. 8.

Chordin is required for the activity of Spemann organizer grafts. Shown here are transplants of pigmented organizers into albino hosts. (A–C) Transplant of a wild-type organizer followed for a few hours, showing how it involutes through the ventral blastopore until it is barely seen by transparency below the ectoderm (dotted line). (D–F) Depletion of Chordin in the organizer graft (Oelgeschläger et al., 2003) prevents all inductive activity, and the transplanted cells remain in the surface of the embryo, becoming epidermis. D, dorsal: V, ventral. Transplantation experiment by E.M.D.R., photographs by J.L. Plouhinec