Sox10E contains distinct cranial and vagal/trunk regulatory elements. (A) Schematic diagram representing dissection of Sox10E fragment, located ∼1-kb downstream of Sox10 locus (UTR in yellow). Two smaller active regulatory fragments embedded within Sox10E, Sox10E1, and E2, each contain a conserved region (red bar) with 70% sequence homology between amniotes. (B) Sox10E2 drives expression in delaminating CNC (arrows) at HH8+; (C) Sox10E1 is first active in migrating VNC at HH15. (D) Sox10E1 activity persists in migrating VNC, trunk neural crest (arrow), and branchial arches 3 to 5 (arrowhead). (E) Table S1 summarizes distinct temporal (HH9–18) and spatial (cranial/vagal/trunk) regulatory activity of Sox10E1 and E2. (Red −) no expression; (green +) EGFP reporter expression.