Secretions and Secretory Granules

Abstract

Earlier light-microscopic studies on classic endocrine organs demonstrated the existence of granular inclusions in the cytoplasm of endocrine cells. In some organs, the granules were recognized to undergo periodical changes in amount and intracellular location due to the secretory activity of the cell. Their histochemical nature was, in a few cases, correlated with the secretory products of the endocrine cell. Thus, it was accepted that these granular inclusions represented the sites of storage of the secretory products which may be collectively called hormones.