<i>Ppip5k2</i>^<i>K</i><i>^</i> mice exhibit late onset degeneration of OHCs in the basal cochlear turn, which detects high frequency sound.

<p>(A) Confocal images of the organ of Corti, labeled with antisera against MYO7A, a hair cell marker, at the apical, middle and basal turns of the cochlea in <i>Ppip5k2</i>^<i>+/+</i>, <i>Ppip5k2</i>^<i>+/K</i><i>^</i>, and <i>Ppip5k2</i>^<i>K</i><i>^</i>^<i>/K</i><i>^</i> mice at P150. In WT mice, the position of dead OHCs are marked with asterisks (*), observed only in the basal turn. In contrast, significantly higher number of OHCs were missing in <i>Ppip5k2</i>^<i>+/K</i><i>^</i>, and <i>Ppip5k2</i>^<i>K</i><i>^</i>^<i>/K</i><i>^</i> mice, which correlates with the high-frequency HL observed in these mice. Scale bar: 20μm. (B) Inner hair cells and outer hair cells were quantified in <i>Ppip5k2</i>^<i>+/+</i>, <i>Ppip5k2</i>^<i>+/K</i><i>^</i>, and <i>Ppip5k2</i>^<i>K</i><i>^</i>^<i>/K</i><i>^</i> mice at P150. For quantification purposes, organ of Corti were isolated from three different mice of each genotype, and the hair cells were counted in 200μm stretches of apical, middle and basal coil regions. No significant difference was observed for the number of IHCs. Whereas in the case of OHC number (mean ± SEM), a statistically significant (*p<0.05, **p<0.01) decrease in OHCs were observed in the basal coil of <i>Ppip5k2</i>^<i>+/K</i><i>^</i>, and <i>Ppip5k2</i>^<i>K</i><i>^</i>^<i>/K</i><i>^</i> mice, which coincide with the high-frequency HL observed at this age in both genotypes.