Neural crest cells do not self-differentiate; instead, they diversify into particular cell types following interactions with other cells, extracellular matrices, growth factors, and hormones. These sources of change can be seem in the premigratory area or once the cells have begun migrating. Several factors can restrict neural crest cells from migrating. They may be restricted by some intrinsic mechanism according to the time they emigrate from the neural tube. Another reason for restriction may be because cells with particular potentials take particular migration routes or because cells encounter and respond to different environmental cues along different pathways.

Generalizations of Differentiation

Trunk neural crest cells that follow the ventral pathway of migration become neuronal and contribute to the dorsal root ganglia. Those that take a more dorsal-lateral route become pigment cells, specifically melanocytes. Cells that migrate later have fewer developmental options. The cells that leave early can take either a dorsolateral or a ventral pathway. The restriction of early migrating cells is ganglionic. Separate lineages of sensory and autonomic neurons are established early in neural crest cell migration from cells that are pluripotential and can form sensory and autonomic neurons or melanocytes. Some of these cells also may give rise to parts of the adrenal medulla.

Cranial neural crest, either late or early migrating cells, seem to have the same differentiating capabilities. Early migratory cells are defined as those migrating from embryos with eight pairs of somites; late migrating cells are those that come from embryos with 12 pairs of somites. Most late migrating cells migrate dorsally and therefore normally contribute less to skeletal tissues than the early migrating cells. They also occupy spaces that early-migrating cells fail to fill. The early migrating cells migrate more medially.

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