The neural crest cells that contribute to the pharyngeal arches delaminate from which brain regions?

• A. Mesencephalon and Rhombencephalon
• B. Prosencephalon and Mesencephalon
• C. Rhombencephalon and Telencephalon
• D. Mesencephalon and Prosencephalon

Answer: (A)

Cranial neural crest cells that populate the pharyngeal arches come from the midbrain and hindbrain regions. The neural crest originates at the border of the closing neural tube, and for the cranial crest that migrates into the pharyngeal arches, the source regions are the mesencephalon (midbrain) and rhombencephalon (hindbrain). These cells migrate into the arches and contribute to much of the craniofacial skeleton and connective tissues. Forebrain regions (prosencephalon) contribute to other cranial structures rather than the pharyngeal arches, so the midbrain and hindbrain are the correct origin sources.