Pentimento: Neural Crest and the origin of mesectoderm

In this idiosyncratic review, we aim to explain our concerns with the current definitions in this field, and in the chiastic words of Samuel Johnson (1781), “… make new things familiar and familiar things new”.1 Then, we will try to distinguish the developmental events crucial to the regulation of Neural Crest development at both cranial and trunk axial levels of vertebrate embryos, and address some of the implicit assumptions that underlie the conventional interpretation of experimental results on the origin and fates of Neural Crest-derived cells. We hope our discussion will resolve some ambiguities regarding both the range of derivatives in the Neural Crest lineage and the conventional understanding that cranial mesectodermal derivatives share a common Neural Crest-derived lineage precursor with components of the PNS.