DEGENERATION PATTERNS OF ACTIN DISTRIBUTION IN THE ORGAN OF CORTI IN 2 GENOTYPES OF MICE

Alterations of the auditory system during ageing and after noise damag e have been studied earlier in two genotypes of mice, CBA/Ca and C57BL /6J, the former of which shows a late-onset hearing loss and the latte r a high susceptibility to ageing and acoustic trauma early in life. T he two strains display similarities to the different types of human ag e-related hearing loss. In the present study, the different patterns o f hair cell degeneration were visualized by phalloidin-labelled actin in the two strains of mice with increasing age. At 1 month of age ther e were no major differences in the actin distribution between the two genotypes. With increasing age, CBA mice retained a regular pattern of actin content in the cuticular plate but some hair cells were missing . In contrast, the C57BL mice showed a severely distorted architecture of the cutis plate (CP) with less actin labelling, missing hair cells and scar formation. The instability of actin in the hair cells of C57 BL mice might result in their high susceptibility to ageing and noise damage.