Ultrastructural characterization of enterochromaffin-type cells in human gastric carcinoma

Ultrastructural characterization has been performed on eosinophilic granular cells occurring in gastric carcinomas. Of these, the present paper dealt with enterochromaffin (EC)-type cells. EC-type cells were identified by the presence of eosinophilic granules, immunoreactivity for serotonin (5 HT) and argentaffinity. Conventional electron microscopy revealed that they bore membrane bound, electron-dense granules of varying size (100-800 nm in shorter diameter), which were larger than those of normal EC cells. Their shapes are round, rod-shaped and concave. The granules are immunolabeled for 5HT by both pre- and post-embedding methods. The preembedding method also disclosed diffuse cytosolic immunoreactivity. Both differentiated-type and undifferentiated-type gastric carcinomas showed essentially the same results. General trends of occurrence of Paneth-like and EC-type cells in gastric carcinomas were also discussed. The present study confirmed that EC-type cells in gastric carcinoma retained basic characteristics of EC cells despite of morphological deviation from the normal cells. It is speculated that they are derived from neoplastic precursor cells with a special differentiation.