Abstract
Abstract: :
Purpose:To study ultrastructual changes of the cornea in zinc-deficient rat fetuses. Methods:Pregnant Wistar Kyoto rats were fed a zinc-deficient diet and distilled and deionized water starting on the 5th day pregnant. Twelve-,17-, and 20- day old fetuses were used. The fetuses of normal rats fed a usual diet were used as controls. Transmission electron micoscopy(TEM) study: enucleated eyes were fixed in 4% glutaralaldehyde and Caufield osmium, embedded in Lubeak 812. The cornea was examined by TEM (Hitachi H-300 and JOEL2100). Results:In Zinc-deficient rats, the microvilli of the epthelium are sparse, and the development of the epithelium is delayed, ribosomes are decreased, tonofibrils sparse with ill-formed bundles, the density of collagen fibers in the corneal stroma is decreased, and mitochondria in the endothelial cells are fewer than in the control rats. Conclusion:The development of the cornea was delayed in all layers in Zn deficient rat fetuses. Zn is related to collagen metabolism and to protein and nucleic acid sythesis as Zn- containing enzymes. Thus Zn deficiency may lead to maldevelopment of the corneal stroma and inactive nuclear division of epithelial cells, Zn is necessary for the development of immature tissue.
Keywords: 370 cornea: basic science • 472 microscopy: electron microscopy • 506 pathology: experimental