Fig. 1. (A,B) An intact tilapia embryo 2 days before hatching (A), and an embryo whose yolk sac has been almost severed from the embryonic body (B). An arrow indicates the incision. (C–F) Incised wounds on the yolk-ball preparations at 0h (C,E) and 3h (D,F) after surgery stained with Trypan Blue (C,D) and observed by scanning electron microscopy (E,F). The wound (arrowheads) had almost healed after incubation for 3h in BSS. Note the symmetrical distribution of melanophores on the dorsal side of the yolk-sac membrane. Scale bars: A–D, 1mm; E,F, 100µm.