Fig. 6. Neural crest cells labeled at stage 22 and fixed for observation at stage 25. (A) Pax2 expression at stage 25. Expression at the mid-hindbrain boundary (mhb) and the otic vesicle (ov) is used to indicate the position of the DiI-labeled cells; (B) Embryo labeled at the hindbrain region near the otic vesicle. At stage 25, labeled cells are found throughout mid-branchial arches; (C) Embryo labeled at the caudal hindbrain region. Cells have migrated ventrally to populate the dorsalmost portion of the caudal branchial arches. Cells have also migrated from the site of origin caudally into the dorsal fin. fm, fin mesenchyme; mhb, mid-hindbrain boundary; ov, otic vesicle; yellow circle, initial position of DiI; yellow arrow, direction and distance of migration of labeled cells along the rostrocaudal axis. Scale bar: 200 µm.