Figure 1. Auditory mechanotransduction phenotype of young postnatal Myo15^sh2/sh2 mice.

A and B, SEM images of Myo15^sh2/sh2 OHCs at postnatal day 9 (P9) (A) and 19 (B). Insets show magnified images of stereocilia. Note stereocilia links in A and their absence in B. C, auditory brainstem responses in P16 homozygous (left) and heterozygous (right) Myo15^sh2 mice. Stimulus type and intensity (dB SPL, sound pressure level) are indicated. Arrows mark the stimulus onset. D, epifluorescent images of Myo15^sh2/sh2 organ of Corti explants (harvested at P3 and kept 3 days in vitro) after incubations with 5 μm FM1-43 for 60 s (left), FM1-43 and 1 mm GdCl₃ for 60 s (middle), or FM3-25 for 6 min (right). E, time course of FM1-43 uptake in Myo15^sh2/sh2 hair cells measured at the confocal optical plane below the cuticular plate. Insets show the actual fluorescent images before and immediately after application of 5 μm of the dye to the apical surface of OHCs. Scale bars: 1 μm (A, B); 10 μm (D). All cells (A and B, D and E) were located approximately at the end of the first (apical) cochlear turn.