Differentiation in normal human buccal mucosa epithelium.

The epithelium of normal human buccal mucosa was studied by light and electron microscopy and stereological procedures in twenty punch biopsies of 10-15 years old females. Morphometric point counting techniques were employed in order to estimate the density of cell membranes in the superficial third of this epithelium. Observations and data suggested that (1) there is a dense and regular papillary body of slender connective tissue papillae which bifurcate within and penetrate the basal two thirds of the epithelium; (2) the epithelium comprises two major cell compartments, namely (a) the formative and proliferating basal and suprabasal cells, and (b) the differentiated but maturing spinous, and the subsurface and surface cells; (3) the major step in differentiation occurs at the boundary between suprabasal and lower spinous cells; (4) cytoplasmic composition is a reliable indicator of differentiation, which occurs prior to cell flattening; and the relative density of filamentous networks is an indicator of maturation; while cell flattening may be the sign of adaptation to functional needs, i.e. distensibility.