Quantitative electron microscopic analysis of the stratified epithelium of normal human buccal mucosa.

The epithelium of normal human buccal mucosa was subjected to stereologic analysis. Ten biopsies were selected from a total of 20 specimens collected from 10 to 15 year old females, and processed for light- and electron microscopy. At two levels of magnification, electron micrographs were sampled from four strata in epithelial ridges and from three strata in regions over connective tissue papillae. Stereologic point counting based on a recently improved system for analyzing stratified epithelia was employed to analyze a toatl of 1820 electron micrographs. Buccal epithelium was found to be 0.48 mm thick, interdigitated by long, slender connective tissue papillae, and comprised of a narrow basal and suprabasal, and a broad, homogeneously structured spinous and surface compartment. From basal to surface layers, the epithelium displayed a differentiation pattern different from that of keratinizing epithelia. This pattern was a function mainly of a drastic density increase of cytoplasmic filaments of a constant 80 A diameter, a corresponding decrease of the cytoplasmic ground substance, the appearance of dark-cored membrane coating granules and individually varying amounts of glycogen deposition. It is suggested that the dense meshwork of filaments which fill 70% of the epithelial cytoplasm in a broad subsurface and surface layer, serves as the functional matrix for epithelial distensibility.