Barbara A. Bohne, Ph.D.
Gary W. Harding, M.S.E.
Dept. of Otolaryngology, Washington University School of Medicine, St. Louis, MO
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Fig. 1 Percent missing hair cells in normal chinchillas as a function of age. Inner hair cell
losses are shown in blue squares along with their regression line (Pearson r = 0.92). Outer hair
cell losses are shown in red circles along with their regression line (Pearson r = 0.87). Inner hair
cell loss averages about 0.3% per year while outer hair cell loss averages about 1% per
year.
Fig. 2 With aging, age pigment (lipofucsin) is found within the outer hair cells
(OHC 1 2
3). This intracellular accumulation grows with age. Age pigment is found in the organ of Corti
even in animals deaf from birth. This suggests that its source is not the normal wear and tear of
signal transduction, but more likely the product of routine cell maintenance.
Last updated 4/15/97