The authors observed the ultrastructure of oral leukoplakia simplex of gingiva, buccal mucosa,.tongue and alveolar ridge. For the purpose of clearly defining the lesions under investigation in this study, leukoplakias were considered to be any white patches on the oral mucous membranes that could not be removed by rubbing and could not be classified clinically or microscopically as another diagnosable disease.
The tissues to be examined were embedded in paraffin for light microscopic study.
The tissues to be examined under the electronomicroscope were fixed in 2.5% glutaraldehyde in 0.1M cacodylate buffer and 1% osmic acid in 0.1M cacodylate buffer, dehydrated with graded alcohol, and treated with propylene oxide, and embedded in Epon. Ultrathin sections were obtained by LKB III ultrotome, stained with uranyl acetate/lead citrate, and examined with Corinth 500EM. The results were as follows:
1. Epithelium of leukoplakia consisted of stratum basale, stratum losum and stratum corneum.
2. There was hyperorthokerotosis or hyperparakeratosis.
3. Granular cells contained a lot number of membrane coating granule showing lamellar
structure, clearing or condensation, and a lot of keratohyaline granule varied in size.
4. An increased concentration of tonofilaments and an increased number of desmosomes were
found: in the stratum spinosum.
5. Basal lamina generally showed its continuity, but in some locatoins, its interreption and multiplication appeared.
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