FIG. 8.

FM 1-43 entry into hair cells through stereocilia. a Dye application to the wild-type (+/+) organ of Corti demonstrated fluorescence primarily within the stereocilia of the single row of inner hair cells (IHC) and of all three rows of outer hair cells (OHC). A repeat image (inset) after an additional 90 s of washout reveals dye within the soma of the inner hair cells (arrow) and outer hair cells (arrowhead). b The pre-application of streptomycin inhibited the uptake of FM 1-43 dye, consistent with the blockage of mechanoelectrical transduction channels. c Hair cells in the heterozygous (+/−) mouse demonstrated normal dye uptake. d Hair cells in the null (−/−) mouse also demonstrated FM 1-43 dye uptake. Note the expected disorganization of the normal inner and outer hair cell regions of the organ of Corti, including a duplicated inner hair cell (arrow), missing outer hair cells (asterisk), and a rotated stereociliary bundle (arrowhead). Scale bar is 25 μm.