Regulation of Melanoblast Migration and Differentiation

Summary 1 The discovery of the relationship between the neural crest and pigment cells is briey reviewed. 2 In all animals studied thus far, neural crest cells are known to migrate along specied pathways and to dierentiate into a variety of cell types. These phenomena are directed by a variety of determining factors. 3 W ith regard to understanding pigment cell migration and dierentiation, �sh have recently contributed in a signicant way primarily because of the large number of mutants that have been isolated in zebrash and other species. Moreover, the clear embryos are amenable to experimental manipulation and visualization. 4 Amphibians have provided extensive opportunities to examine the movement and dierentiation of a variety of pigment cell types, and in this case a number of mutants have been studied in some detail. However, this system has not been exploited to its full potential. 5 Although many reports of pigment variants exist in reptiles, little work has been done on developmental aspects of reptil- ian chromatophores. 6 Our understanding of the cellular and biochemical controls of pigment cell development has been greatly enhanced by work done in avian systems. Recently the development of methods to up- and downregulate gene expression in the avian embryo has contributed importantly to the understanding of melanogenesis in this system. 7 The many coat color mutants of mice provide extensive opportunities for better understanding the motive forces in pigment cell development. 8 A comparative evolutionary approach to studye pigment cell development will continue to be essential for understand- ing how such discrete cells (pigment cells) from a well-dened progenitor cell population (the neural crest) have dierenti- ated and evolved.