Scanning electron microscopic study of surface of human oral mucosa.

The surface ultrastructure of the healthy oral mucosa of humans was studied using SEM as follows: dorsum of the tongue (10 specimens), buccal mucosa (5), floor of the mouth (3), hard palate (5), and gingiva (10). One part of each formalin-fixed sample was processed routinely using the system of critical point drying for scanning electron microscopy. The other part of the specimen was embedded in paraffin blocks and stained with hematoxylin-eosin for light microscopy. With SEM at low magnification, the surface structure of the oral mucosa at different areas of the oral cavity was smooth with some desquamating cells. Only the tongue mucosa with its papillae formed a specialized mucosa. The hairs of the filiform papillae were covered by microorganisms, whereas on the oral mucosa there usually was little or no colonization by microorganisms. At high magnification, the surface structure of the superficial epithelial cells was pitted or microplicated. On keratinized epithelium the surface structure was pitted, whereas on non-keratinized epithelium it was microplicated. On cell boundaries some variation could also be seen; in keratinized epithelium these boundaries were overlapping and in non-keratinized epithelium they were tight.