Lineage of neurons and glia in chick dorsal root ganglia: analysis in vivo with a recombinant retrovirus

We used retrovirus-mediated gene transfer to study the lineage of neural crest cells in chick embryos. Individual crest cells were infected before they migrated from the neural tube, and their clonal progeny were subsequently revealed in sensory ganglia and associated structures by a histochemical stain for the viral gene product (lacZ). We found that crest cells were multipotential in several respects. (1) Many clones contained both ventrolateral (VL) and dorsomedial (DM) neurons, which had been suggested to be lineally distinct. (2) Many clones contained both large and small neurons, which are known to innervate distinct targets. (3) Many clones contained multiple glial subtypes, e.g. both Schwann cells, which ensheath axons, and satellite cells, which ensheath neuronal somata. (4) Many clones contained both neurons and glial cells. On the other hand, a sizeable minority of clones was homogenous, e.g. they contained only neurons or only glial cells—suggesting that some progenitors may be, or become, restricted in potential. Finally, this study provides the first opportunity to compare directly the two methods currently available for tracing cell lineage in vertebrate embryos, retroviral infection and tracer injection: our results and those of Bronner-Fraser and Fraser (1989), who used the latter method, provide complementary but consistent views of crest lineage.