Histological study on the effect of zinc deficiency on the lingual epithelium of adult male albino rats

ABSTRACT

Twelve healthy adult male albino rats weighing [200 - 300 mg] were used in this study aiming to demonstrate the possible histological alterations that may occur in the epithelium covering the lingual filiform papillae and the ventral surface of the tongue as a result of zinc deficiency. They were divided into two equal groups; a control and zinc deficient ones. Zinc deficient diet [less than 1ppm zinc] was fed to the animals of the zinc deficient group daily for 42 days. Whereas, the animals of the control group received the same diet supplemented with zinc carbonate to increase zinc concentration to 55 ppm. At the time of sacrifice, the animals of the two groups were anaesthetized by ether inhalation and their tongues were dissected out carefully and processed for light and electron microscopes examination. Light microscope examination of the dorsal surface of the tongue of zinc deficient rats revealed the presence of deformity of the filiform papillae with exfoliation of the horny layer of their covering epithelium. Also, the epithelium showed thickening of both prickle and granular layers. The cells of the later appeared large in size, irregular and lightly stained. In addition, the covering epithelium of the ventral surface appeared thick and keratinized with obliteration of the underlying connective tissue papillae. Electron microscope examination of the filiform epithelium of the same group demonstrated the cytoplasm of the basal cell layer with many vacuoles, Many irregular keratohyalin granules of different shapes and sizes were observed in the strata spinosum and granulosum, in addition to the presence of relatively thick tonofilaments. Also, partial separation of the cells of the granular layer and partial exfoliation of the covering horny layer were noticed. In conclusion, the present results showed that zinc deficiency resulted in deformity and hyperkeratosis of the filiform papillae, in addition to thickening and keratinization of the ventral surface epithelium. This alteration of the normal architecture of the lingual epithelium may be, together with the associated clinical complications, an available investigation for tissue zinc deficiency