Abstract
While it is well established that neural crest cells migrate to give rise to a variety of cell types and tissues, the migratory patterns among individual neural crest derivatives have not been fully worked out. Such knowledge is important not only in relation to the mechanisms of neural crest migration and differentiation, but also in understanding the ontogeny of the PNS. Of special interest in the latter regard is the origin of sympathetic ganglion cells and their innervation, since studies on ganglion cell innervation have suggested that the matching between pre- and postganglionic neurons might be based on their early positions along the neuraxis (see preceding paper). In the present study, I have used the quail-chick transplantation technique to examine the migratory patterns of the precursors of sympathetic ganglion cells, dorsal root ganglion cells, and melanocytes that originate from 1 or 2 segments of the trunk neural crest. My results indicate that precursors of sympathetic ganglion cells, on average, migrate 2 segments rostrally and 3 segments caudally. Thus, individual sympathetic ganglia comprise neurons that originate from up to 6 segments of the neuraxis. Precursors of melanocytes also migrate along the rostrocaudal axis, but to an even greater extent than sympathetic ganglioblasts. In contrast, precursors of dorsal root ganglion cells do not migrate at all along the rostrocaudal axis (although they migrate along a ventromedial pathway to give rise to the dorsal root ganglia of the same segmental level). The number of neural crest segments contributing to each sympathetic ganglion is approximately equal to the number of spinal cord segments contributing to its innervation.(ABSTRACT TRUNCATED AT 250 WORDS)
