GFP expression in the GFP ++ of G1 embryos during development from 1 to 3 days post-fertilization. Left side (a, c, e), views on dark field. Right side (b, d, f), views through GFP filter. (a, b) Stage 1 (1 dpf, 1 hpf). Lateral views of one-cell egg. Animal pole at the top. GFP expression was observed in the cell. (c, d) Stage 9 (2 dpf, 27 hpf). Dorsal views of the embryo. GFP expression was observed in the cells of 40% epiboly, especially strong in the cells forming embryonic shield. (e, f) Stage 12 (3 dpf, 46 hpf). Dorsal views of the embryo. GFP expression was observed in the entire body of embryo. About ten somites form along the body axis. Scale bar, 1 mm.