Fig. 5.

FGF/Ets is not sufficient for expression of the horseshoe Wnt target genes at the dorsal midline, whereas Wnt signaling is. (A) In situ hybridization on gastrula-stage embryos injected with ets2 mRNA and β-gal tracer (red) in the two dorsal blastomeres at the four-cell stage. Sections are of whole embryos pictured. Bottom row shows higher magnification of boxed areas from row above. (B) In situ hybridization on gastrula-stage embryos incubated in the Wnt agonist BIO starting at stage 8-9 until collection.