Fig. 11

Putative relationship between FGF and associated GRN components during caudal denticle morphogenesis. As observed widely throughout epithelial appendage development, for example during feather placode development, FGF—shh positive feedback loops which promote mesenchymal bmp4 are likely to promote early caudal denticle placode morphogenesis. bmp4 may then act as an internal inhibitor, limiting the size of the final unit. FGF signalling can also promote mesenchymal expression of dlx2. This is a hypothetical GRN based on findings from previous research, gene expression data (Figs. 4, 5, 6, 8) and small molecule inhibition of FGF signalling during early caudal denticle morphogenesis, using SU5402 (Figs. 9, 10)