Steel factor (SLF) and its cognate receptor, c-kit, have been implicat
ed in the generation of melanocytes from migrating neural crest (NC) c
ells during early vertebrate embryogenesis. However, the source of SLE
in the early avian embryo and its precise role in melanogenesis are u
nclear. We report here that NC cells themselves express and release SL
F protein, which in turn acts as an autocrine factor to induce melanog
enesis in nearby NC cells. These results indicate that NC cell subpopu
lations play an active role in the determination of their cell fate an
d suggest a different developmental role for the embryonic microenviro
nment than what has been previously proposed. (C) 1997 Academic Press.