Aging of the olfactory system of male rats a histological and ultrastructural study I-olfactory and vomerosensory epithelia

ABSTRACT

In the present study, age-related histological, histochemical, and ultrastructural changes in both the olfactory epithelium [OE] and the vomeronasal organ [VNO] have been investigated. A total number of 30 albino rats were used in this study Animals were divided equally into two groups; [adult group] and [aged group]. The OE of the aged animals was reduced in thickness, with a relative disturbance in the zonal arrangement of its layers and invaded by acini of Bowman's glands. A basal nuclear-free zone and apical pale cells were also observed within the aged OE. Both mitotic figures and apoptotic bodies were seen in the aged OE. Periodic acid schief-Alcian blue [PAS-AB,] reaction revealed an increase in the PAS-reaction both in the apical and basal parts of the aged OE. Alkaline phosphatase reaction showed a marked reduction in the enzyme activity within the basal cell layer with the appearance of scattered positive cells with the aged OE. On the other hand an increase in the enzyme activity of Bowman 'S glands was observed. The most frequent ultrastructural finding within the aged OE was the accumulation of dense inclusion bodies within the mature ORNs. Less frequently filamentous inclusions were also detected. SEM investigation revealed reduction in the olfactory area and shortening in the olfactory cilia. In aged animals the vomerosensory cells showed vacuolated cytoplasm. Intraepithelial blood capillaries appeared irregular. Histochemically, the PAS-reaction was increased in the apical processes of the supporting cells and reduced in the VS cells whereas alkaline phosphatase along the apical surface was not affected. Ultrastructurally, vomerosensory cells exhibited dilatation of most organelles mainly sER and Golgi bodies, numerous clear vesicles of variable sizes, multiple electron-dense inclusions and lipofuscin granules. VNO are more vulnerable to the aging process than the OE. Sensory cells in particular are more affected than other cell types