From which neural tube regions do neural crest cells that contribute to the pharyngeal arches originate?

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

Answer: (A)

Cranial neural crest cells that populate the pharyngeal arches come from neural tube regions in the midbrain and hindbrain. As the neural tube closes, crest cells from the mesencephalon (midbrain) and rhombencephalon (hindbrain) detach and migrate ventrally into the pharyngeal arches. There, they differentiate to form much of the skeletal and connective tissue of the face and neck, as well as contribute to various cranial structures. Forebrain regions (the prosencephalon, telencephalon, and diencephalon) don’t contribute these cranial neural crest cells to the pharyngeal arches in this pattern, which is why the midbrain and hindbrain origin best explains their presence in the arches.