Secretory granules

Mast cells are connective tissue cells that can be readily identified by the abundance of secretory granules in the cytoplasm. These granules have a reddish color with H & E staining (left) and a purplish-blue color with toluidine blue (right). Mast cell granules contain heparin, histamine and protease enzymes that function in the inflammatory response. 1000x, 1000x