Bone Morphogenetic Proteins have recently been determined to mediate neural crest inductions and migration in chick embryos. The BMP-4 and BMP-7 molecules are growth factors in the TGFb gene family, and are expressed in the epidermal ectoderm adjacent to the neural tube. After neural induction, these BMPs can promote migration of neural crest from the neural tube and activate neural crest markers such as slug. The inductive activity of the ectoderm can be mimicked in vitro by the addition of BMP-4 and BMP-7 which are first expressed in the epidermal ectoderm, as discovered by K.F. Liem. Links between Hox genes and BMP in neural crest induction are also being investigated. (Le Douarin, 27)