The control of onset of melanoblast differentiation inXenopus larvae

Summary Studies on the time of first appearance of melanophores in uniformly-sized vesicles of hypomeric tissues containing different masses of neural crest tissues suggest that regional differences in the time of first appearance of trunk melanophores inXenopus are regulated by regional variation in the population density of melanoblasts.This work was supported by the Science Research Council and presented in a thesis, University of Glasgow.The author thanks Professor D. R. Newth for his interest and valuable criticisms.