Fig. 3. Experiment B (see Fig. 1D). (A,E,I) Dorsal views of E3 chick embryos grafted at E2 with a fragment of neural tube deprived of midline cells (A) alone (experiment B1); (E) with a notochord (experiment B2); (I) on a layer of SHH-producing cells (experiment B3). (B-D, F-H and J-L) Consecutive sections of each embryo at the level of the graft, hybridized with Shh (B,F,J) and Pax3 probes (C,G,K) or examined for cell death using the TUNEL assay (arrowheads) (D,H,L). En: endoderm; No, notochord; NT, neural tube; Shh, SHH-producing cells; So, somite.
