The cephalic neural crest of amniote vertebrates is composed of a large majority of precursors endowed with neural, melanocytic, chondrogenic and osteogenic potentialities

Abstract

In the amniote embryo, the neural crest (NC) has the unique capacity to give rise to neuronal and glial cells in the peripheral nervous system (PNS), melanocytes and mesenchymal cells including those forming the head skeleton and connective tissues. In the trunk, mesenchymal cells are derived from the mesoderm. The question was raised whether the NC-derived head mesenchyme arises from a lineage separate from the neural-melanocytic one, or if both skeletogenic and neural-melanocytic derivatives originate from a common putative stem cell in the early cephalic NC. We discuss here these issues and present experimental data that provide evidence for the multipotency of NC cells (NCC), focusing on those at the origin of the craniofacial skeleton. Recent work of in vitro clonal culture revealed that the vast majority (92% of clonogenic cells) of the cephalic quail NCC are capable to yield osteoblasts together with neurones, glial cells and melanocytes. A common pluripotent progenitor for chondrocytes, osteocytes, neurones, glial cells, melanocytes and myofibroblasts has been identified and is present in the early cephalic NC at the frequency of 7 to 13% of clonogenic cells depending on the environmental conditions. Together with recent reports that multipotent NC-related progenitors persist in adult tissues in rodents and humans, these results reinforce a stem cell model for the generation and maintenance of NC-derived lineages during embryogenesis and in adult tissue homeostasis.