To investigate where the CS/DS chains affect cell migration, we performed transplantation experiments with green fluorescent protein (GFP) as a lineage tracer. First, we homotypically grafted CNC explants from embryos that were co-injected with a morpholino oligonucleotide and GFP mRNA into uninjected sibling hosts at stage 17 (Fig. 6A). Cells from the control-MO-injected CNC grafts migrated ventrally and formed well-orchestrated mandibular, hyoid and branchial streams (Fig. 6B). In contrast, the migration of the Dse-MO-injected CNC cells was disturbed and only a few labeled cells reached their correct destination (Fig. 6C). When GFP+ CNC cells were transplanted into control- and Dse-morphant host embryos (Fig. 6A′), their cell migration was normal (Fig. 6D,E). These findings suggest that DS-epi1 is needed in the CNC graft, but apparently not in surrounding tissue, which indicates a tissue-autonomous function of CS/DS PGs in CNC cell migration.
