Wnt pathway genes are upregulated already at E12.5 in the region where supernumerary mammary placodes form.

Expression of (A) Wnt10b, (B) Wn10a, (C) Kremen2, (D) Lgr4, (E) β-cat, (F) Tbx3, and (G) Nrg3 in Eda-/-, wild-type and K14-Eda embryos. Note correlation of levels of Wnt10b, Wnt10a, Kremen2, and Lgr4 with the Eda status (A-D).Further, Wnt10b, Kremen2, Lgr4, and β-cat show an early stripe-like expression pattern in the region where supernumerary mammary placodes emerge (A, C-E). (Scale bar: 500 μm.)