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Fig. 2 Continuous organizing properties of the early gastrula margin. (A) Various gastrula marginal grafts performed at the animal pole of host embryos. Donor embryo, left, animal pole view; host embryo, right, lateral view. 0°, dorsal margin (DM); 45°, dorsolateral margin (DLM); 90°, lateral margin (LM); 180°, ventral margin (VM). (B-I) In situ hybridizations for hoxC12b (B,D,F,H) and for krox20 (C,E,G,I) on embryos displaying secondary tails (B,C), a trunk-posterior head (D,E), a posterior head (F,G) and axial structures (H,I). Arrowheads indicate secondary axes. (J) The frequency of the different structures induced by grafts of the various pieces of margin. Number (n) of embryos analyzed: DM, 15; DLM, 18; LM, 24; VM, 15. B-I, lateral view, anterior to the left, dorsal to the top.