Pluripotent neural crest cells in the developing skin of the quail embryo

The neural crest, a migratory population of embryonic cells, gives rise to a wide range of differentiated cell types in the mature vertebrate organism, including the melanocytes of the skin. Little is known about the developmental potentials of neural crest cells toward the end of their migratory phase. We have therefore used in vitro analysis to examine the developmental potential of mesenchymal cells derived from explants of trunk epidermal ectoderm of the quail embryo. Melanocytes which differentiated in the cultures could be identified by their content of melanin granules. To detect different neuronal cells, the cultures were stained with antibodies including anti-dopamine-beta-hydroxylase (anti-DBH), which characterizes sympathoadrenal cells, and AC4, an antibody which recognizes the stage-specific embryonic antigen-1 (SSEA-1) that is expressed by cells in the sensory neuron lineage of the quail embryo, but not by sympathoadrenal cells. Seventy-eight percent of the population of neural crest-derived cells seeding the ectoderm around stage 21 gave rise to colonies containing melanocytes only. Twenty percent, however, generated mixed colonies that contained melanocytes, DBH+ cells, SSEA-1+ cells, and unidentified, unpigmented cells. Small numbers of colonies containing fewer phenotypes were also seen. With increasing embryonic age, the number of colonies containing multiple phenotypes declined, until by stage 30 all neural crest colonies contained melanocytes only. Some colonies had been marked at the single-cell stage, and this provided additional confirmation that each colony-type could be generated from a single cell. Thus the significant finding in this study is that a substantial fraction of the neural crest cells arriving early in the ectoderm are pluripotent cells that are able to give rise to pigment cells, to sympathoadrenal cells, to primary sensory neuron precursors, and possibly to other cells which were not identified here. This observation may have implications for our understanding of the mechanisms that control neural crest cell migration and differentiation.