Influence of age on hair cell loss in the rabbit cochlea.

The surface preparation technique was used for a study of cochlear hair cell loss as a function of age in rabbits 1 week, 6 months, 1 year, and 4 years old. Cytocochleograms from these animals were prepared which indicated damaged or missing hair cells over the entire spiral organ from the apical to the basal coil. The loss in the mean percentage of total outer hair cells (OHC) and inner hair cells (IHC) appeared to increase linearly with increasing age, with a statistically significant correlation. The cell loss was similar in all three rows of OHC in each of the age groups. In animals up to 1 year of age, areas of OHC loss were localized in the apical and basal coils. In 4-year-old rabbits, OHC degeneration had become progressively accentuated and widespread. The pattern of IHC loss was somewhat similar to that of OHC. Age-related hair cell loss in the rabbit is comparable to that in the rat, monkey, and human cochlea.