Time Sequence of Degeneration Pattern of the Organ of Corti after Acoustic Overstimulation: A Transmission Electron Microscopy Study

Female pigmented guinea pigs were exposed to a 3.85 kHz pure tone of 120 dB SPL for 22.5 min. The exposed animals were sacrificed after varying post-exposure intervals (5 min, 4 and 24 h, 5 and 28 days). Transmission electron microscopical examination was performed after serial-sectioning in areas of maximum damage and both basal to and apical to this region. By serial-sectioning, the degradation pattern of the individual cell structures in the organ of Corti could be studied in relation to post-exposure time and proximity to the well-demarcated area of maximum damage in the organ of Corti. The results provide further information on the non-reversible changes leading to degeneration and loss of sensory and supportive structures in the organ of Corti.