Fig. 3. Early Nodal signaling before DVE formation is essential to specify EmVE. In pre-DVE control embryos (A,C,E,G), which have not yet upregulated HexP-GFP expression (E5.25, see Materials and methods for accurate staging of embryos), Lim1, Fgf5, Fgf8 and Bmp2 are specifically expressed in the EmVE. By contrast, all of these markers fail to be induced in Nodal mutants (B,D,F,H). Note that Fgf5 and Fgf8 also show expression in the epiblast of wild-type embryos, which is downregulated in Nodal^lacZ/lacZ null mutants (C,E,D,F).