Comparative electron microscopic features of normal intermediate and metaplastic pyloric epithelium.

The ultrastructural appearance of surface epithelial cells of normal and abnormal pyloric epithelium is presented. In addition to areas of complete intestinal metaplasia (IM) an incomplete metaplasia is described which contains poorly differentiated mucous cells, goblet cells, an occasional immature absorptive cell as well as the mature mucus-secreting surface epithelial cells of normal pyloric epithelium. This type of epithelium frequently appeared hyperplastic and showed alterations in the surface microvilli, terminal webs, plasma membranes and mucin granules. Apical vesicles, small electron-dense bodies and larger electron-dense multivesicular bodies were also found in the intermediate cells of incomplete IM and in the mature absorptive cells of complete IM. The intermediate cells described here may be synonymous with the sulphomucin-secreting cells found in adenocarcinomas of the stomach and oesophagus.