Rostrocaudal differences within the somites confer segmental pattern to trunk neural crest migration

Abstract

Neural crest cells are one of the most migratory and pleiotropic of embryonic cells types. These cells originate within the central nervous system, but emigrate from the neural tube shortly after its closure. They subsequently migrate along well characterized pathways to populate numerous and diverse derivatives ranging from sensory and autonomic ganglia of the peripheral nervous system to the cartilage and bone of the face. It is reported that neural crest migration is intimately linked to both the formation and segmentation of the somites. After differentiation of somites into dermomyotome and sclerotome, the sclerotomal compartment is subdivided into rostral and caudal halves. Although overtly similar, the caudal half sclerotome has a higher cell density and different molecular markers. Notably, ephrins (Eph) are selectively expressed in the caudal half sclerotome whereas their cognate Eph receptors are expressed on neural crest cells and rostral sclerotomal cells. Functional interactions between Eph receptors and ligands appear to restrict neural crest cells to the rostral half sclerotomal domain. This in turn leads to their segmental migration and the subsequent metameric distribution of neural crest-derived sensory and sympathetic ganglia.