The Pax6 protein is a transcription factor. Heterozygotes for normal Pax6 have reduced eye size. Homozygotes for abnormal Pax6 lack eyes completely. Pax5 is critical for development of the eyes and nose. Neural Crest Neural crest cells break off the top of the neural tube at the time that the tube closes.
Migration occurs through the anterior portion of each somite.
Slug protein may be important in initiating migration. The timing of N-cadherin expression in the surface membranes coincides with the premigratory and postmigratory stages of neural crest differentiation. Different regions in the same embryo and same regions in different species have various signal molecules. Pluripotency of trunk neural crest cells Location of neural crest cells within the embryo regulates the differentiation. Exchange the vagal and thoracic regions in chimeras, the area of transplantation determines the neurotransmitter that is expressed.