Fig. 5. Conditional Notch1 deletion in the ear causes supernumerary hair cell formation in the cochlea that resembles the Dll1^hyp/-Jag2^-/- mutant phenotype. (A,B) Lectin-stained whole-mount cochleae demonstrating the large increase in both inner and outer hair cells in Foxg1-Cre Notch1^flox/- cochleae (B) when compared with Notch1^flox/- cochleae (A), which appear normal. (C,D) Examples of the organ of Corti in sections from control (C) and Foxg1-Cre Notch1^flox/- mutant (D) cochleae stained for myosin VIIa (hair cells, green) and p27kip1 (support cells, red). (E) Hair and supporting cell counts from 32 mid-modiolar sections, as shown in C and D (counts were done as for the Dll11/Jag2 double mutants). Sections from three ears were counted for each group, either control or Foxg1-Cre Notch1^flox/-. Counts of both hair cells (HCs) and supporting cells (SCs) were significantly different between mutant and control cochleae (^*P<0.001, ^**P<0.0001; Student's t-test). Similar to the Dll1/Jag2 double mutant cochleae, the increases in hair cells did not equal the supporting cell losses (P<0.0001; one-way ANOVA). Scale bars: in B, 100 µm for A,B; in D, 50 µm for C,D.