Figure 7

Structural damage and functional loss of the cochleae examined at 14 days after exposure to an intense noise at 120 dB sound pressure level (SPL) for 1 hour. (A) Typical pathology of the outer hair cells in the first cochlear turn, from which the organ of Corti tissue was collected for the transcriptional analysis. The tissue was stained for prestin to illustrate outer hair cells. Arrows point to the areas of missing cells. Note that outer hair cell losses are sporadically distributed in the basal turn of the cochlea. (B) A cochleogram showing the distribution of hair cell lesions in the basal part of the cochlea (35 to 100% from the apex). The bracket indicates the region from which the organ of Corti tissue was collected for the transcriptional analysis. (C) Comparison of ABR thresholds tested before and two weeks after noise exposure. The acoustic overstimulation caused a relatively flat threshold elevation with an average threshold shift ranging from 23.8 to 35.4 dB at the four tested frequencies (2-way ANOVA, F = 403.8, df: 1,88, P = 0). n = the number of cochleae used for each condition.