FGF signaling is required for initiation of feather placode development.

Morphogenesis of hairs and feathers is initiated by an as yet unknown dermal signal that induces placode formation in the overlying ectoderm. To determine whether FGF signals are required for this process we over-expressed soluble versions of FGFR1 or FGFR2 in the skin of chicken embryos. This produced a complete failure of feather formation prior to any morphological or molecular signs of placode development. We further show that Fgf10 is expressed in the dermis of nascent feather primordia, and that anti-FGF10 antibodies block feather placode development in skin explants. In addition we show that FGF10 can induce expression of positive and negative regulators of feather development and can induce its own expression under conditions of low BMP signaling. Together these results demonstrate that FGF signaling is required for the initiation of feather placode development and implicate FGF10 as an early dermal signal involved in this process.