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Fig. 2. Activation of Notch signaling on mesoderm, neural plate and neural crest development. Two-cell stage embryos were injected with NICDGR mRNA in one blastomere, treated with dexomethasone either directly after the injection (A,C,E) or at stage 12 (B,D,F), and cultured until stage 25 (A,B) or stage 18-19 (C-F). Subsequently, the expression of distinct markers was analyzed. The side of the injection is indicated with an arrowhead. (A,B) Immunostaining of somites with the 12/101 antiserum. Note the expansion of the somite in the injected side following early activation (A), and the normal morphology after late activation (B). Following activation at stage 2, 78% of embryos demonstrated somite expansion (n=70), whereas activation at stage 12 did not produce any expansion of the somites (0%; n=87). (C,D) In situ hybridization to visualize Sox2 transcripts in the neural plate. Activation at stage 2 (C) leads to an expansion of the neural plate (65% of embryos with expanded neural plate; n=83), whereas activation at stage 12 (D) produces no effect on the neural plate (100% normal; n=92). (E,F) In situ hybridization to visualize Xslug transcripts in the cephalic neural crest. Activation at stage 2 (E) produces an inhibition in the expression of this neural crest marker (58% of inhibition; n=102), whereas activation at stage 12 (F) produces an expansion of Xslug expression (expanded in 75% of embryos; n=152). |
