SCANNING ELECTRON-MICROSCOPIC EVALUATION OF AGE-RELATED-CHANGES IN THE RAT VESTIBULAR EPITHELIUM

An ultrastructural study was performed to assess age-related changes i n the vestibular end organs of Fischer 344 rats. The surfaces of the m aculae and cristae from 3-, 12-, and 24-month-old Fischer 344 rats wer e observed by use of scanning electron microscopy. Age-related changes in the morphology of the vestibular neuroepithelium included a substa ntial loss of hair cells, as well as a reduction in the number of kino cilia and stereocilia on those that remained. These changes were great est in the central upper regions of the three ampullae. In aged animal s a greater area of the neuroepithelial surface was covered with micro villi, and in some instances, giant cilia were found among the microvi llous surfaces. In contrast, there were few differences among the thre e age groups in the number and condition of hair cells in the saccules and utricles. The changes observed in the cristae may contribute to t he age-associated impairment of vestibular function. If similar change s occur in human beings, these could in part account for the presbycus is observed in the elderly.