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Male rats were subjected to hypervitamin A treatment by daily intraperitoneal injections of 150 UI Arovit per g body weight. Another group of rats were injected intraperitoneally with saline solution for ten days and were used as controls. The results indicated that: 1) the body weight of animals treated with excess vitamin A was decreased; 2) histological analysis of the esophageal epithelium in treated animals showed increased thickness, characterizing a picture of hyperplasia and hypertrophy. On the basis of the results obtained, we suggest that excess vitamin A may act on the esophageal epithelium by direct action on the epithelial structures, stimulating and increase of the mitosis, and on the epithelium (mediated by the adrenals), resulting in increased thickness due to the concentration of a larger number of more immature cells. These alterations were more evident in the lower esophageal third.

Daily administration of 150 IU vitamin A/gram of body weight in mice, during 10 days, led the authors to observe: submandibular glands showed acini of slightly reduced size, with lower cells whose contours were not always sharp and containing smaller number of cytoplasmic granules. The nuclei of the acinar cells were reduced in volume. The granulose ducts were similar to those of the controls in size but showed signs of degeneration as well as cell nuclei of reduced volume. The striated ducts were smaller than those of the controls, while the excretory ducts were dilated, with lower cells and nuclei of reduced volume. General examination showed that the hypervitaminotic animals had more abundant connective stroma than the controls. The glandular structures were studied morphometrically and estereologically.