Changes in soft palate taste buds of rats due to aging and zinc deficiency--scanning electron microscopic observation.

The effects of aging and zinc deficiencies on taste were studied. The soft palate of zinc-deficient old rats, prepared by feeding with a zinc-deficient diet, were studied by a light microscope and a scanning electron microscope, and comparative examination was made on the morphological changes in soft palate papillae and taste buds of young normal rats and control old rats. In the case of young normal rats, papillae similar to lingual fungiform papillae were observed on the soft palate; one taste bud per one papilla was observed. The papillae were concentrated in the central area of the soft palate continuing from the hard palate. In the case of old rats, decrease in the number of papillae, flattening of papillae, exfoliation and atrophy of mucosal epithelium and leveling of microplicae were observed. In the case of zinc-deficient old rats, the above-mentioned tendencies were more significant. While dense substance and microvilli were observed in taste pores of taste buds of young normal rats, these were found to decrease or disappear in the zinc-deficient old rats.