Age-related changes in microvillar cells of rat olfactory epithelium.

The nature and function of microvillar cells (MVCs) of the mammalian olfactory epithelium (OE) are little understood. Previous studies have examined MVC morphology in the developing and mature OE, but not in the aged OE. The present study investigated the effect of aging on MVCs of the OE in male Sprague-Dawley rats using histological and immunohistochemical methods. OE of aged rats contained MVCs with marked hypertrophy and swollen end-feet, which reached the basement membrane. Such MVC features were not observed in the young OE. These MVC changes were more conspicuous in proximity to severely degenerated olfactory receptor neurons (ORNs) and supporting cells. The ratio of the number of MVCs to that of supporting cells increased with aging; however, MVCs in the aged OE were not proliferating cell nuclear antigen-immunoreactive. In addition, the total cell population was decreased in the aged OE. Thus, our results suggest that MVCs are non-neuronal and that they are more resistant to aging compared to ORNs and supporting cells.