Cytoplasmic Processes in Normal and in Malignant Oral Epithelium

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Abstract
The cytoplasmic processes in preinvasive and invasive carcinoma of the human oral epithelium were examined and compared with the corresponding structures of the normal epithelium. Two types of cytoplasmic processes occur in the intercellular space of both normal and pathologic epithelium. One type is long and slender, the other wide-based, tonofilament-containing and associated with desmosomes. The distribution of the cytoplasmic processes varies between the different cellular strata of the normal epithelium. In preinvasive and invasive carcinoma, where there is great variation in stratification regularity, both types of cytoplasmic processes vary widely in number from cell to cell, and additional types of cytoplasmic processes appear in the intercellular space. The border between the basal cell and the connective tissue is characterized, in the normal tissue, by a certain regularity, and the presence of a continuous basement membrane. In carcinoma this border is irregular, and the basement membrane may be absent, extremely thin, multilayered or composed of an atypical material. The presence of various cytoplasmic processes, all without a basement membrane, contributes to the irregular pattern. There are also changes in the subepithelial tissue: the normal pattern, dominated by collagen fibrils, is destroyed and replaced by electron-lucent areas. It was suggested that the destructive activity is an early feature preceding the invasive process. It was concluded that these prevailing and well-defined changes may be of diagnostic importance and provide information on the migratory activity of the malignant cell.