Neural Crest(redirected from Ganglion ridge)
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A strip of ectodermal material in the early vertebrate embryo inserted between the prospective neural plate and epidermis. After closure of the neural tube the crest cells migrate into the body and give rise to parts of the neural system: the main part of the visceral cranium, the mesenchyme, the chromaffin cells, and pigment cells. The true nature of the neural crest eluded recognition for many years because this primary organ has a temporary existence; its cells and derivatives are difficult to analyze when dispersed throughout the body. The fact that mesenchyme arises from this ectodermal organ was directly contrary to the doctrine of the specificity of the germ layers.
Neural crest no doubt exists, with similar qualities, in all vertebrate groups, including the cyclostomes. It has been most thoroughly studied in amphibians and the chick. See Germ layers
the fold of ectoderm that borders the neural, or medullary, plate during neurulation in chordates and man. The cells of the neural crest become distributed over the neural tube after neurulation, forming the ganglionic primordia. The neural crest gives rise to the spinal and sympathetic ganglia, the visceral skeleton, the pigment cells, and the connective tissue layer of the skin.