ABSTRACT
Electron microscopic examinations of the ultrastructure of normal esophageal epithelium of an adult man revealed submicroscopic features of each epithelial layer. A specific structure of epithelial cells is represented by tonofibrils. Glycogen is found only in the prickle-cell and superficial layers. In the latter there were some signs of incomplete keratinization. Hyperplasia of the prickle-cell and superficial layers epithelium was accompanied by accumulation of glycogen and marked parakeratosis with disintegration of the nucleus, formation of keratin fibrils, and destruction of desmosomal bonds. Dysplastic changes in the esophageal epithelium were heterogenous and presented a whole set of ultrastructural rearrangements. We distinguish two variants of dysplasia. In the "dark-cell" variant there were hypertrophy and hyperchromia of the nucleus, deep invaginations of the nuclear membrane, swelling of the mitochondria, appearance of myelin-like structures in the matrix, increased number of free ribosomes, polysomes, and lipids, formation of tonofibrillar-keratohyaline complexes, increased number of cytoplasmic processes. The "clear-cell" variant was characterized by nuclear hypertrophy, marked dilation of cisterns of the rough endoplasmic reticulum, extensive vesicle formation, keratohyaline granules, few cytoplasmic outgrowths, dilation of the intercellular space.
