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. Author manuscript; available in PMC: 2015 Oct 5.
Published in final edited form as: Curr Top Dev Biol. 2015 Jan 21;111:461–495. doi: 10.1016/bs.ctdb.2014.11.014

Figure 3. Arrangement of germ layers and neural crest cells in the branchial arches.

Figure 3

(A) sagittal view of an embryonic day 9.5 (E9.5) mouse embryo showing branchial arches (BA) 1–3. The external surface of each arch is ectoderm. Neural crest cells (NC) in three distinct streams populate the arches. The most anterior stream contains NC from the midbrain and rhombomeres 1 and 2 from the hindbrain. Rhombomeres 3 and 5, the white regions between streams of yellow neural crest produce very few neural crest cells. (B) Schematic of a coronal section through the arches of the embryo in (A). Branchial arches consist of external ectoderm, an endodermal lining, a core of mesoderm, and neural crest cells from the midbrain and hindbrain. The boundaries of the arches are defined by points of contact between endoderm and ectoderm: the pharyngeal pouches.