THE EFFECT OF CERTAIN LUBRICATING AGENTS AND COARSE FOODS UPON THE CORNIFICATION OF THE ORAL MUCOSA OF THE WHITE RAT

¹ Department of Anatomy, College of Dentistry, and the Graduate School of Arts and Science, New York University, New York, N. Y.

1. The gingival mucosa of the white rat maintained on a diet of Purina Chow shows a stratum corneum consisting of several layers of nonnucleated polygonal cells showing distinct cell boundaries, the deeper layers of which show no marked differentiation from the underlying stratum granulosum.

2. Rats maintained on a diet of kernel corn or corn meal have a stratum corneum consisting of several layers of compressed, flattened cells between which cell membranes are not apparent and whose deeper layers show a clear line of demarcation from the underlying stratum granulosum. The stratum spinosum is composed of small cells with finely granular basophilic cytoplasm with barely discernible cell outlines.

3. The above effects are more readily observable in the gingiva of the mandible; the maxillary gingiva in all cases remaining identical.

4. The addition of 10 per cent vegetable oil to the corn diets acts to antagonize their dehydrating and compressing effects upon the mandibular gingiva. The stratum corneum of these animals consists of large polygonal cells with distinct cell outlines, and the stratum spinosum is composed of voluminous cells with deeply staining centrally placed nuclei.

5. The action of vegetable oil is a local one and is probably due to its lubricating property, for mineral oil produces entirely analogous results. The oils apparently prevent dehydration, and the cells remain soft and full of cytoplasm.

6. The epithelium of the hard palate, already dehydrated, shows no tendency toward changing in response to the mastication of a coarse diet, and also shows no tendency toward alteration when subjected to a fat-supplemented diet.