Tail regeneration after embryonic grafting of neural crest or of posterior ventral epidermis+mesenchyme. (A-C) A piece of GFP transgenic posterior neural crest was grafted to the same positions in wild type hosts. The labelled embryos were grown to tadpoles (B), amputated at stage 48 and allowed to regenerate for 7 days (C). Red lines indicate the amputation level. (D) A single melanophore in a regenerated tail from such an experiment, with contracted pigment and abundant GFP in the cytoplasm. (E-H) Similar experiment with graft of posterior ventral epidermis+mesenchyme (PVEM). In (H) is shown a section of the regenerate with two melanocytes, neither of which is labelled. White scale bars 500 μm; black scale bars, 20 μm.