Size of nucleus and nucleolus in quantitative electron microscopy on orthokeratinized leukoplakias.

Eleven leukoplakias of the homogeneous orthokeratotic type and control areas in the same patient were studied by means of standardized electron microscopic preparations of biopsy material and by methods of stereology applied to electron micrographs. In leukoplakias, nuclei and nucleoli were consistently enlarged at three epithelial levels, nucleoli in the basal cells averaging twice the control size. Comparison with specimens of mucosa of the hard palate showed that the enlargement of nuclei and nucleoli in orthokeratinized leukoplakias was in excess of the normal size differential between inherently orthokeratinized and nonkeratinized regions of the human oral mucosa. This suggests an abnormal stimulation of protein-synthetic activity even in this prognositcally "benign" type of leukoplakia.