Embryonic Induction

Vertebrate embryos rely extensively upon inductive interactions to diversify the number of different kinds of cells in the embryo. Induction is the process by which one group of cells produces a signal that determines the fate of a second group of cells. This implies both the capacity to produce a signal (ligand) by the inducing cells and the competence of the responding cells to receive and interpret the signal via a signal transduction pathway. Amphibians …

…organizer. Evidence in favor of this hypothesis again comes from a comparison of the fate map and specification map: About 60% of muscle is derived from ventral mesoderm (Slack, 1994). However, explanted ventral mesoderm forms little or no muscle (Dale and Slack, 1987). Muscle is formed by ventral mesoderm when it is juxtaposed with the organizer. This dorsalization of the ventral mesoderm occurs during gastrulation. (See Browder et al., Fig. 12.5, Gilbert, Fig. 15.17; Kalthoff, Fig. 9.23; Wolpert et al., 1998, Fig. 3.26)