In vitro clonal analysis of progenitor cell patterns in dorsal root and sympathetic ganglia of the quail embryo.

The possible presence of pluripotent cells in dorsal root (DRG) and sympathetic ganglia (SG) of the quail embryo has been investigated by in vitro clonal analysis. Both types of ganglia originate from the neural crest. At, or soon after, initiation of emigration from the neural tube, the neural crest appears as a mixed population of pluripotent cells and cells with more restricted developmental capacities. In the present study it was determined that pluripotent cells and precursor cells with restricted developmental potentials are also present in early DRG and SG, and that their proportions change with progressing age of the embryo. As in the neural crest, cells in one class are at least tripotent, able to give rise to pigment cells, sensory neurons, and cells in the sympathoadrenal lineage. Cells in the other class appear to have lost the melanogenic potential, but generate cells in the sensory neuron and sympathoadrenal lineages. In addition, there are two types of cells that seem to be committed to the melanogenic and sensory neuron lineages, respectively. Apparently committed melanogenic cells within the DRG are not detected after the first third of embryonic development, whereas precursor cells that are at least bipotent and generate both types of neurons persist in both DRG and SG at least through the first half of embryonic development. Neurogenic cells that are apparently committed to the sensory neuron or sympathoadrenal lineages were observed in the appropriate type of ganglion only, suggesting that location-specific cues influence the choice of phenotype generated by pluripotent neural crest cells.