At the ultrastructural level the inflamed oesophageal epithelium shows a variety of lesions. These include mitochondrial damage, intracellular oedema, membrane whorls and dilation of the endoplasmic reticulum and the appearance of keratohyaline and parakeratosis granules. The basement membrane shows changes ranging from thickening to areas of loss of continuity. There is an increase in the anchoring fibrils. The spaces between the cells are enlarged and contain varying amounts of debris rich in neutral mucosubstances. There are less membrane-coated granules in the inflamed epithelium than in the normal. The intra-epithelial intrusive cells demonstrated were lymphocytes and neutrophil polymorphs.

The histochemistry of lipids and mucosubstances in normal human oesophageal epithelium were studied in biopsies obtained from 24 patients undergoing investigations of the upper gastro-intestinal tract. Neutral fat droplets, 1-2 mum in diameter, were present in all layers, the greatest number being in the functional layer cells. No unsaturated lipids or fatty acids were demonstrable. Much glycogen was present in the cytoplasm of the prickle and functional cell layers as demonstrated by PAS (and diastase digestion) techniques. The intercellular space of the most superficial of the functional cell layer contained neutral and sialic acid-rich acid mucopolysaccharides. These may be important in protecting the epithelium against physical and chemical trauma.

The appearances of this intercellular junctions in normal and in inflamed oesophageal epithelium are described. Typical hemidesmosomes occur along the abluminat aspect of the basal cells. Desmosomes are most frequent in the prickle cell layer, where desmosome fields may occur, and in the lower functional cell layer. Their fate in the upper layers is not known. Gap junctions are few in the basal cell layer and rare in the most superficial layers. They are maximal in the prickle cell layer. Tight junctions only occur in inflamed tissue between the most superficial cells usually as part of a lateral intercellular junctional complex that also contains belt desmosomes. They may represent attempts by a non-keratinised epithelium to increase its defences against toxic luminal contents.

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