How neural induction is achieved in vertebrates is hotly debated. The default model of neural induction, which is based on experiments in frog ectodermal explants, proposes that inhibition of bone morphogenetic protein(BMP) signalling specifies neural fate. In chick and zebrafish embryos,however, neural induction is initiated by fibroblast growth factor (FGF)signalling. Delaune and colleagues now report that neural induction in whole frog embryos requires both FGF signalling and BMP inhibition (see p. ). By using BMP and FGF signalling inhibitors, the researchers show that pre-gastrula ectodermal FGF signalling is required for neural induction in frogs. They propose that,in addition to inhibiting BMP, FGF signalling directly drives neural induction. However, definitive proof of a BMP-independent role for FGF signalling in frog neural induction awaits the identification of a transcriptional target that acts in a pathway that is essentially required for neural specification.
