Oxyntic cells of the gastric mucosa in the resting state contain prominent tubulovesicles. Previous electron microscopic studies showed that the number of tubulovesicles was reduced and that the cell surface membrane was increased, in the secreting state.
To clarify the related mechanisms, tannic acid was used for the tracer of the cell surface and the acid secreting and non-acid-secreting oxyntic cells in frog stomach were studied.In the acid-secreting oxyntic cells induced by gastrin, fusion between the tubulovesicles and cell surface membrane was apparent.
After this fusion, the tubulovesicles may become attached to the cell surface membrane, and an increase in the area of the apical free surface would ensue.