Ultrastructure and cytochemistry of the gastric mucosa of a reptile, Tiliqua scincoides.

The gastric mucosa of a reptile, the lizard Tiliqua scincoides, has been examined by light and electron microscopy. The gastric pits lead into glands that are extensively coiled in the proximal stomach but become progressively shorter and straighter in the distal stomach. The following epithelial cell types have been identified: (i) Surface mucous cells (SMC) line the entire lumenal surface as well as the pits. They contain mucus granules that stain with periodic acid-Schiff and, like the granules of mammalian SMC, commonly contain an electron dense core that appears not to be mucus (periodic acid-chromic acid-silver methenamine nonreactive). (ii) Glandular mucous cells are present in glands throughout the mucosa. They are probably homologous with the mucous neck and antral gland cells of mammals; like SMC their mucus granules contain nonglycoprotein cores. (iii) Oxynticopeptic cells (OPC) are the predominant cell type in the proximal gland but become infrequent distally. Their fine structure resembles that of OPC in other nonmammalian vertebrates, with features like those of both parietal cells and zymogen cells of mammals. (iv) Endocrine cells of three different types have been identified. Two of these show close similarities to the EC and ECL cells of mammals.