Fig. 1. Isochronic and orthotopic graft of segmental plate from quail to chick. (A) Scheme of a graft. (B) AcLDL-DiI labeling of the vascular network; 13 somite-pair embryo; ventral view, truncal level. The whole vascular network is labeled. The arrow indicates the level of the last-formed somite pair. At this level, the paired aortae are positioned lateral to the somites, whereas they are in more central positions at more cephalic levels. Lines indicate the levels of sections in C,D. Scale bar: 800 µm. (C,D) Unilateral last somite + segmental plate removal. 13 somite-pair embryo; cross-sections, QH1 staining. (C) Level of the third last-formed somite. The ectoderm has been removed. (D) Segmental plate level. The right segmental plate has been removed with no damage to the aorta. The aorta is positioned lateral to the segmental plate. Scale bar: 70 µm. (E) Isolated last somite + lateral plate mesoderm, QH1 staining. No QH1⁺ cell was detected in 18 out of 20 grafts analyzed. Scale bar: 100 µm. Ao, aorta; E, ectoderm; NT, neural tube; S, somite.