Fig. 2. The prospective line –1 was already determined to make a fissure. (A,B) Transplantation of a piece of PSM containing level –1 into a non-segmented level (–1.5). The size of the graft largely corresponded to a prospective somite. Anterior and posterior halves of the graft were labeled with DiI (red) and DiO (green), respectively. On the operated side, a boundary (arrow) formed between the DiI- and DiO-labeled regions, and along this fissure epithelialized miniature somites were present (bracket). (C,D) In the control, an isotopic transplantation (–1.5 into –1.5) did not produce a boundary between DiI- and DiO-labeled areas. (B,D) Sagittal frozen sections of embryos treated similarly to A and C, respectively. Stained for F-actin with Phalloidin (white).