Fig. 2: Stereocilia growth is disrupted in jordan mutant hair cells.
A–F Representative SEM images of stereocilia bundles from Myo15a+/+, Myo15ajd/jd, and Myo15ash2/sh2 OHCs (A, C, E) and IHCs (B, D, F) at P8. In Myo15a +/+ mice, both IHC and OHC bundles display the characteristic staircase architecture with 3 stereocilia ranks of increasing height (labeled in white font). IHC and OHC bundles from either Myo15ajd/jd and Myo15ash2/sh2 mice are shorter in height than the wild-type bundles. Myo15ajd/jd stereocilia taper in height towards the periphery of the bundle (arrow), and additional stereocilia rows are visible (arrow head). Myo15ash2/sh2 hair cells also have additional stereocilia rows, but they lack graded thickness and height. G Projected heights of tallest (row 1) OHC stereocilia at P8 are 1.2 ± 0.1 µm (Myo15a+/+, 58 stereocilia from 4 mice), 0.8 ± 0.1 µm (Myo15ajd/jd, 60 stereocilia from 4 mice), and 0.4 ± 0.1 µm (Myo15ash2/sh2, 50 stereocilia from 2 mice). H Projected heights of tallest (row 1) IHC stereocilia at P8 are 2.2 ± 0.2 µm (Myo15a+/+, 47 stereocilia from 4 mice), 1.3 ± 0.1 µm (Myo15ajd/jd, 47 stereocilia from 4 mice), and 0.9 ± 0.1 µm (Myo15ash2/sh2, 30 stereocilia from 2 mice). ****, P < 0.0001, Brown–Forsythe and Welch ANOVA with Dunnett’s T3 multiple comparisons test. Representative images are from mid-cochlear turn. Data are mean ± SD. Scale bar, 2 µm.
