Neural Crest Cell and Placode Interactions in Cranial PNS Development

The cranial peripheral nervous system (PNS), including the cranial nerves and their associated sensory and parasympathetic ganglia, forms from two embryonic cell populations during development: cranial NCC and the ectodermal placodes. While the placodes contribute the paired special sense organs and the majority of the neurons of the cranial sensory ganglia, NCC migrate throughout the head and differentiate into a wide variety of neuroglial and non-neuroglial cell types. In addition to being required to generate the specific derivatives of the cranial PNS, reciprocal interactions between the NCC and placodal cell populations are currently being identified. Here, we describe the interactions between NCC and both placodal ectoderm and placodal derivatives at a molecular and cellular level and discuss their importance for the coordinated development of cranial PNS with both the CNS and the periphery. © 2014 Elsevier Inc. All rights reserved.