Purpose: To examine the conjunctiva and cornea of riboflavin-deficient rats with scanning (SEM) and transmission (TEM) electron microscopes.
Materials And Methods: Three-week-old Wistar Kyoto rats were fed a riboflavin-deficient diet (0.05 mg riboflavin/100 g) for 3 months. As a recovery experiment, rats which had been on a riboflavin-deficient diet for 3 months were given water with 1 mg riboflavin/300 ml for 2 months. The conjunctiva and the cornea were examined with SEM and TEM.
Results: The serum riboflavin level was significantly lower in the riboflavin-deficient group than in the controls. In rats on a riboflavin-deficient diet for 3 months, SEM showed decreased microvilli and microplicae in the superficial epithelium of the conjunctiva and a decrease in the number of goblet cells. The cornea showed many dark cells and a marked decrease of microvilli and microplicae. In the riboflavin-deficient rats, TEM of the conjunctiva showed a decrease of microvilli and microplicae in the most superficial epithelial cells, a decrease in the layers of the epithelium and a marked decrease in the number of goblet cells, while the cornea had decreased microvilli and microplicae in the superficial epithelium, dark wing cells, loss of the basement membrane and hemidesmosomes of basal cells, cell debris and degenerative stroma cells and deposits of dense bodies in the subepithelial layer of the stroma. In rats recovered from riboflavin deficiency, the conjunctiva and cornea showed no abnormalities.
Discussion: Riboflavin plays a role in the development and maintenance of the surface structures of epithelial cells. Riboflavin may also be necessary for the development and maintenance of goblet cells.
Conclusion: Riboflavin is essential for maintaining the structure and function of the ocular surface.
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