Quantification of YFP- and VAChT-positive synapses at the OHC regions at 2 months old. (A) The whole cochlea from base to apex. The exact locations for 10 and 28 kHz are indicated on the overlay panel after mapping. (B) High power micrographs at 10 (upper panel) and 28 kHz (low panel) of OHC areas. The rows of OHCs are numbered OHC1, OHC2, and OHC3. (C) Quantification data for each row of OHCs at 10 kHz (data from 5 animals). (D) Quantification data for each row of OHCs at 28 kHz (data from three animals). Mean values (+/- standard error of the mean) were obtained by averaging counting data from an average of 15 OHCs per row.