Further studies have shown that the NC cells which participate in facial skeletogenesis correspond to the anteriormost region of the body axis... » More

Further studies have shown that the NC cells which participate in facial skeletogenesis correspond to the anteriormost region of the body axis where the genes of the Hox cluster are not expressed. If the forced expression of Hoxa2, Hoxa3 and Hoxb4 (the most anteriorly expressed Hox genes) is induced in this part of the neural fold, brain development is deeply affected with anencephaly and no skeletogenesis takes place in the face which fails to develop. This phenotype is reproduced when the anterior neural fold is surgically removed before NC emigration. One of the early consequence of these experiments concerns the expression of Fgf8 which disappears in the anterior neural ridge (mostly) and in the branchial arch ectoderm. We found that the phenotype resulting from the excision can be rescued by providing the developing head with an exogenous source of Fgf8, thus showing the important role of this signaling molecule in head development. The next study (in progress in my laboratory) concerns the molecular mechanisms through which the NC affects Fgf8 production during cephalogenesis in Vertebrates.

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