Figure 2. Juvenile Manf^fl/fl;Pax2-Cre B6 mice show hair bundle disorganization.

(A, B) At P22, there is no outer hair cell (OHC) or inner hair cell (IHC) death in the cochleas of cKO mice, shown in the 45-kHz (high frequency) region by myosin 7a immunostaining. The three rows are OHCs are marked by numbers. (C, D) Comparison of phalloidin labeling in the mutant and control cochleas at P22 reveals the OHC hair bundle disorganization in the 45 kHz region of mutant specimens. Arrowheads point to hair bundle imperfections. (E, F) SEM analysis at P22 confirms the hair bundle disorganization (arrows) in mutant specimens. (G, H) High-magnification views of 45-kHz OHC hair bundles display problems in individual stereocilia to hold their upright position in the bundle in mutant specimens (arrow). (I, J) High-magnification views of 45-kHz IHC hair bundles show comparable organization between the genotypes. Abbreviations: B6, C57BL/6J strain; cKO, conditional knock out; Ctrl, control; IHCs, inner hair cells; OHC, outer hair cell; SEM, scanning electron microscopy. Scale bars: (A) 5 μm A, B; (C) 5 μm C, D; (E) 5 μm E, F; (G) 1 μm G, H; (I) 1 μm I, J.