Abnormal tau protein expression was immunohistochemically examined in biopsied human olfactory mucosa. The olfactory mucosa of 25 patients with olfactory disturbances, whose structures were relatively preserved, was immunostained with a polyclonal antibody derived from neurofibrillary tangles from the brains of patients with Alzheimer's disease. Abnormal tau protein-immunoreactivity was found in the olfactory vesicles, dendrites and perikarya of the olfactory receptor cells in the epithelium and olfactory nerve bundles in the lamina propria. This immunoreactivity in the olfactory nerve bundles was observed in patients in their teens to 80's, and the immunoreactivity of the olfactory vesicles and dendrites of the olfactory receptor cells was widely distributed in patients in their 30's to 70's. On the other hand, the immunoreactivity of the perikarya of the olfactory receptor cells was observed only in patients in their 50's and 60's. These results indicate that abnormal tau protein accumulation of perikarya is a pathological change and is related to aging of the olfactory neurons.
