Fig. 3.

IBC/IPhC repopulation fails after ablation in juvenile and adult mice and leads to IHC loss and hearing impairment. (A) Representative optical projections of whole mounts from the apical turn of the cochleae of GlastDTA and control mice induced with tamoxifen at P15 and P16; cochleae were analyzed 3 wk later at P37 (parvalbumin⁺ HC are shown in red; GLAST⁺ IBCs/IPhCs are shown in green; nuclei labeled with Hoechst 33342 in blue). The timeline of tamoxifen induction (T) and cochlea collection (C) for analysis is shown below the image. (B) Representative optical projection of whole mounts from the apical turn of the cochleae of GlastDTA and control mice induced with tamoxifen at P21; cochleae were collected 3 wk later at P41. The timeline of tamoxifen induction and cochlea collection for analysis is shown below the image. (C) Quantification of the number of IHCs, IBCs/IPhCs, and IPCs in 160 μm of the apical turn of cochleae of GlastDTA and control mice at P41–42 after P21 induction (mean ± SEM, n = 4). SCs were counted as number of Sox2⁺ nuclei in the specific location of the cell type in control samples. Statistical differences in cell numbers were determined by two-way ANOVA followed by Student t test with Bonferroni correction. (D) ABR thresholds measured from GlastDTA and control mice at ages P41–42 after P21 induction (mean ± SEM, n = 6–7). Statistical differences in thresholds at each frequency analyzed (4, 6, 12, 16, 22, 32, and 44 kHz) were determined by two-way ANOVA followed by Student t test with Bonferroni correction. (Scale bars: 10 um.) **P < 0.01, ***P < 0.001.