Shark embryos neural tubes were vitally labeled with DiI for 24hrs. Stage 25 embryo: Tail end (A) and caudal trunk (B, C) show segmental migration of neural tube derived cells (arrows) as well as a ventral line of DiI cells (arrowheads). (D) Shows 2 sets of migrating DiI cells in the out-tract of the heart (arrows). Stage 27 embryo: DiI this older embryo shows labeled cells in neural tube and segmentally migrating cells (arrows in E, G, H), ventral locations (red arrows in H), branchial arches (arrows in F) and turning rostrally (arrowhead in G).