Hoxb1 neural crest preferentially form glia of the PNS

The vertebrate cranial neural crest cells give rise to many complex derivatives of the head, neck, and face, including neuronal and glial cells that act in concert for proper development of the anterior-peripheral nervous system. Several genes have been implicated in the processes of neural crest specification, migration, and differentiation; among these are the hox gene clusters. To determine the fates of hox-expressing cranial neural crest, we describe the results of a genetic lineage analysis by using the Cre/loxP system to drive the activation of different ROSA26 reporter alleles under the regulation of the hoxb1 locus. By targeting the 3' untranslated region of the hoxb1 gene, we have preserved endogenous gene activity and have been able to accurately follow the fates of the cells derived from the hoxb1 expression domain. Emphasis was placed on identifying the cell and tissue types that arise from the rhombomere 4-derived neural crest. Our results demonstrate that, in addition to forming much of the cartilage, bones, and muscle of the ears and neck, a significant population of rhombomere 4-derived neural crest is fated to generate the glial component of the seventh cranial nerve.