Hk. Song et al., FIBROBLAST GROWTH-FACTOR-2 CAN REPLACE ECTODERMAL SIGNALING FOR FEATHER DEVELOPMENT, Proceedings of the National Academy of Sciences of the United Statesof America, 93(19), 1996, pp. 10246-10249
The initiation and morphogenesis of cutaneous appendages depend on a s
eries of reciprocal signaling events between the epithelium and mesenc
hyme of the embryonic skin. In the development of feather germs, early
dermal signals induce the formation of epidermal placodes that in tur
n signal the mesoderm to form dermal condensations immediately beneath
them. We find a spatially and temporally restricted pattern of transc
ription for the: genes that encode fibroblast growth factor (FGF) 2 an
d FGF receptor (FGFR) 1 in developing feather germs of the chicken emb
ryo. PGF-2 expression is restricted to the epidermal placodes, whereas
FGFR-1 expression is limited to the dermal condensations. Transcripti
on of these genes could not be detected in skins of scaleless (sc/sc)
embryos that fail to develop feathers as a result of an ectodermal def
ect, Treatment of sc/sc skins with FGF-2 results in the formation of f
eathers at the site of application of the growth factor and the induce
d feathers express FGFR-1 in their dermal condensations. Thus, we have
established FGF-2 as an epidermal signal in early feather germ format
ion. The observation that FGF-2 can rescue the mutant phenotype of sc/
sc embryos suggests that PGF-2 either is, or is downstream from, the s
ignal that the sc/sc mutant ectoderm fails to generate.