The peptide endothelin 3 (EDN3) is essential for normal neural crest development 
in vivo, and is a potent mitogen for quail truncal crest cells in vitro. It is 
not known which subpopulations of crest cells are targets for this response, 
although it has been suggested that EDN3 is selective for melanoblasts. In the 
absence of cell markers for different precursor types in the quail crest, we 
have characterised EDN3-responsive cell types using in vitro colony assay and 
clonal analysis. Colonies were analysed for the presence of Schwann cells, 
melanocytes, adrenergic cells or sensory-like cells. We provide for the first 
time a description of the temporal pattern of lineage segregation in neural 
crest cultures. In the absence of exogenous EDN3, crest cells proliferate and 
then differentiate. Colony assay indicates that in these differentiated cultures 
few undifferentiated precursors remain and there is a low replating efficiency. 
By contrast, in the presence of 100 ng/ml EDN3 differentiation is inhibited and 
most of the cells maintain the ability to give rise to mixed colonies and clones 
containing neural crest derivatives. A high replating efficiency is maintained. 
In secondary culture there was a progressive decline in the number of cell types 
per colony in control medium. This loss of developmental potential was not seen 
when exogenous EDN3 was present. Cell type analysis suggests two novel cellular 
targets for EDN3 under these conditions. Contrary to expectations, one is a 
multipotent precursor whose descendants include melanocytes, adrenergic cells 
and sensory-like cells; the other can give rise to melanocytes and Schwann 
cells. Our data do not support previous claims that the action of EDN3 in neural 
crest culture is selective for cells in the melanocyte lineage.