Figure 6
Potential migratory pathways for late neural crest cells and melanoblasts. (A) Anti-HNK1 antibody indicated reappearance of migratory neural crest cells in the dorsal neural tube (*) at G16. Paired round areas of HNK-1 positive cells were visible dorsolateral to the neural tube and adjacent to the surface ectoderm (black arrows). (B) At G17, HNK-1 positive cells appeared to follow two migratory pathways: a dorsolateral pathway underneath the surface ectoderm for some of the migratory cells and a pathway where cells travel from the CSA over the dermomyotome laterally (red arrow) or ventrally between the dermomyotome and the sclerotome (orange arrow). (C) PNA was not seen in the dorsal surface ectoderm, carapacial mesenchyme or in or around the dermomyotome, thus allowing entry of migratory neural crest cells to both dorsolateral and medial pathways. (D) Mitf-positive melanoblasts were visible on top of the neural tube, in the CSA, adjacent to the surface ectoderm and in the dermomyotome (boxed area shown in E) and in at G17. (E) The mediodorsal tip of dermomyotome had Mitf-positive cells. (F) Mitf-positive cells were detectable between the dermomyotome and the sclerotome. (G) At G21, c-Kit-positive melanocytes were observed in both the dorsolateral and medial pathways. Some Mitf- and c-Kit-positive cells are indicated by arrows. Scale bar approx. 1 mm (A,B), 100 μm (C,D) and 200 μm (E). c, vertebral cartilage; d, dermomyotome; drg, dorsal root ganglion; l, lung; nt, neural tube; r, rib.
