The concept of the epithelial-mesenchymal transition (EMT) arose from developmental biology, (see ref. 1) where EMT occurs in many situations, each being predictable, stereotyped and with the outcomes often dramatic. The EMT of the neural crest (NC) is an example of this event in development. In its own right; the NC has been ranked as a “fourth germ layer” by Hall.[2] The tissues and structures to which the NC gives rise is widespread in the body and diverse in cell types, ranging from craniofacial connective tissues to peripheral nerve and glial cells to skin pigment cells.[3] In addition, abnormalities involving NC development seem to be disproportionately represented in human birth defects. The NC is important for evolutionary research too, because it is the only organ system unique to vertebrates. Its appearance in evolution is suggested to have enabled the massive adaptive radiation of these chordates. Technically, the experimental approaches for developmental biology, described as “cutting, labeling and pasting”,[4] have shown the NC to be a particularly accessible, manipulatable and robust subject, with relatively straight-forward evaluation of the results in terms of altered developmental patterns. Thus because of its importance and technical advantages, the NC is probably the most studied developmental EMT.