Restriction of the fate of early migrating trunk neural crest in gangliogenesis of avian embryos.

Trunk neural crest is the source of peripheral nervous tissue, the adrenal medulla and pigment cells. To quantitatively assay the potency of neural crest to form each derivative tissue, we isolated fragments of neural crest from quail embryos and transplanted them into the migration pathways of chicken embryos. In the resultant chimeras, we counted the quail cells derived from grafts distributed in the dorsal root ganglia, the sympathetic tissues around the aorta and the spinal nerves. Descendant cells of quail neural crest derived from the brachial or lumbosacral and lower levels were more abundant in the dorsal root ganglia than in the sympathetic tissue, while those derived from adreno-medullary levels were more abundant in the sympathetic tissue than in the dorsal root ganglia. No correlation was seen between the distribution pattern of quail cells and the rostrocaudal levels of graft site in chick embryos. These findings suggest that the developmental potency of truncal neural crest in gangliogenesis is restricted in the early phase of their migration and differs along the rostrocaudal axis, although it is not clear whether this restriction reflects determination of each crest cell. The size of the rudiments of the dorsal root ganglia in the normal embryo differed along the rostrocaudal axis, these differences being consistent with those in the fate of the neural crest at a given somite level.