Granulating Mast Cell | © Edmond Alexander
A mast cell contains many granules rich in histamine and heparin. Mast cells are best known for their role in allergy and anaphylaxis, but they also play an important protective role in wound healing and defense against pathogens. When activated, mast cells rapidly release their granules and various hormonal mediators. They can be stimulated to degranulate by direct chemical or physical injury, cross-linking of IgE receptors, or by activated complement proteins.