Fig. 6. Notch1 signaling augments Wnt signaling in the otic placode. (A) Wnt reporter and Dlx5 mRNA expression is increased in conditionally overexpressing Notch1-ICD (cN1ICD) embryos in whole mounts and corresponding mid-placode transverse sections. Dotted outline demarcates the otic cup; red arrowhead indicates the mediolateral otic region. (B) Wnt reporter expression in transverse sections of control and cN1ICD; Wnt reporter embryos. Wnt reporter mice were co-immunostained with anti-β-galactosidase (β-gal; red) and anti-GFP (green) antibodies. Note that only the medial part of the expanded placode expresses the Wnt reporter. The inset shows anti-β-galactosidase staining in a normal Wnt reporter mouse. Brackets in A and B indicate that the ectopic lateral placode region is negative for Wnt reporter and Dlx5. (C) Wnt reporter and Dlx5 expression is diminished in Notch1 mutants relative to in controls. Brackets indicate the otic placode. (D) A comparison of Pax8 and Foxi2 expression in Notch1 mutant, cAct and Notch1; cAct double mutant littermates. Arrowheads indicate otic expression. Scale bars: 50 µm.