MIGRATION AND COLONIZATION PATTERNS OF HNK-1-IMMUNOREACTIVE NEURAL CREST CELLS IN LAMPREY AND SWORDTAIL EMBRYOS

Migration and colonization patterns of neural crest cells were analyze d histochemically in embryos of the brook lamprey, Lampetra reissneri, and the swordtail, Xiphophorus helleri, using HNK-1 monoclonal antibo dy, which recognizes migratory neural crest cells and crest derivative s in many groups of vertebrates including teleosts. We demonstrated th at HNK-1 recognizes a subpopulation of naural crest cells and crest de rivatives in the lamprey as well as in the swordtail. In the trunk of lamprey and swordtail embryos, HNK-1-positive cells were observed in t he major migratory pathways of neural crest cells, that is ventral and dorso-lateral pathways. In the swordtail embryos, neural crest cells in the ventral pathway were ubiquitously observed along the rostro-cau dal axis at the neural tube level, but at the notochord level their mi gration was restricted to the middle region of the somite. In the lamp rey, by contrast, no HNK-1-immunoreactive neural crest cells migrated ventrally beyond the notochord level in the ventral pathway at axial l evels behind the gill pouch region. This migration pattern of neural c rest cells in the lamprey trunk might be closely related to the absenc e of anatomically distinct, sympathetic chains in the lamprey, which i s one of characteristic features of the lamprey's body organization. F urthermore, we found dorsal pathways, which extended to the embryonic dorsal fin, of neural crest cells in both swordtail and lamprey embryo s. In the lamprey, dorsal cells (Rohon-Beard cells) and cells that res emble chromaffin cells immunoreacted with HNK-1.