Neural Crest Contributions to the Development of the Vertebrate Head

The neural crest is a major source of mesenchyme in the head,but not the body, of the vertebrate embryo. For some of thesemesenchymal derivatives, the differences between the normalfates of cranial and trunk neural crest cells are not necessarilydue to differences in the potentials of the cells for the variousderivatives, but reflect a lack of interaction with appropriateinductive tissues. Chondrogenic potential, however, is restrictedto those axial levels which normally give rise to cartilage.This chondrogenic subpopulation is not homogeneous, even priorto neural crest cell migration, cells from different axial levelsdisplay differences in migratory and morphogenetic abilities.While the events which give rise to these segregations havenever been examined, some models have been proposed for theestablishment of the neural crest itself.