FGF10 is a mesenchymally derived stimulator for epidermal development in the chick embryonic skin

The development of avian cutaneous appendages, feathers and scales, is known to arise from the epithelial-mesenchymal interaction. Here we show that FGF10 is associated with this developmental process as an early signal from mesenchymal cells underlying nascent cutaneous placodes. Expression of Fgf10 was detected in the mesenchymal cells underneath the developing placodes. Forced expression of Fgf10 in the femoral skin suppressed expression of Shh and a zinc finger gene snail-related (cSnR), while induced expression of Bmp2 in the interbud region, resulting in thickening of the epidermal layer. Furthermore, forced expression of Fgf10 in the foot skin caused marked ingrowings of the epidermis. The cells in the epidermal ingrowings expressed beta-catenin, proliferating cell nuclear antigen, and an epidermal stem cell marker p63. These results support the idea that FGF10 is a mesenchymally derived stimulator of epidermal development through crosstalk with bone morphogenetic protein (BMP), beta-catenin, and other signaling pathways.