BMP signaling is essential for development of skeletogenic and neurogenic cranial neural crest

BMP signaling is essential for a wide variety of developmental processes, T o evaluate the role of Bmp2/4 in cranial neural crest (CNC) formation or di fferentiation after its migration into the branchial arches, we used Xnoggi n to block their activities in specific areas of the CNC in transgenic mice . This resulted in depletion of CNC cells from the targeted areas. As a con sequence, the branchial arches normally populated by the affected neural cr est cells were hypomorphic and their skeletal and neural derivatives failed to develop. In further analyses, we have identified Bmp2 as the factor req uired for production of migratory cranial neural crest. Its spatial and tem poral expression patterns mirror CNC emergence and Bmp2 mutant embryos lack both branchial arches and detectable migratory CNC cells. Our results prov ide functional evidence for an essential role of BMP signaling in CNC devel opment.