[Ultrastructure of squamous epithelium in esophageal dysplasia and squamous cell cancer].

Electron microscopic examination of the oesophageal squamous cell carcinoma revealed the presence in the tumour of both undifferentiated and differentiated squamous cells. Keratinocytes appeared and the signs of keratinization were more pronounced in the cytoplasm of differentiated cells. Dysplastic changes were observed at the periphery of the primary node. Two main variants of dysplasia (dark-cell and clear-cell) were distinguished, this at the ultrastructural level being the reflection of the direction of differentiation and the degree of cell maturity in the dysplastic foci. With the exception of few cases with a cell polymorphism in the foci of a severe dysplasia, dysplastic changes of the squamous epithelium were characterized by a monotonous ultrastructural cell composition. The dysplastic cells were distinguished by a degree of differentiation and high synthetic activity.