Spatiotemporal cellular movement and fate decisions during first pharyngeal arch morphogenesis

Cranial neural crest (CNC) cells contribute to different cell types during embryonic development. It is unknown whether postmigratory CNC cells undergo dynamic cellular movement and how the process of cell fate decision occurs within the first pharyngeal arch (FPA). Our investigations demonstrate notable heterogeneity within the CNC cells, refine the patterning domains, and identify progenitor cells within the FPA. These progenitor cells undergo fate bifurcation that separates them into common progenitors and mesenchymal cells, which are characterized by Cdk1 and Spry2/Notch2 expression, respectively. The common progenitors undergo further bifurcations to restrict them into osteogenic/odontogenic and chondrogenic/fibroblast lineages. Disruption of a patterning domain leads to specific mandible and tooth defects, validating the binary cell fate restriction process. Different from the compartment model of mandibular morphogenesis, our data redefine heterogeneous cellular domains within the FPA, reveal dynamic cellular movement in time, and describe a sequential series of binary cell fate decision-making process.