Artwork based on a scanning electron micrograph (SEM) of a single human mastocyte (mast cell), found in connective tissues, typically around blood vessels, airways in lung & the peritoneal lining of the body cavity. Their role is in the synthesis & release of heparin, histamine, and other substances involved in the control of the permeability of blood vessels and airway diameter during the immune response to injury or inflammation. Microvilli are seen projecting from the surface, whose bumpy appearance is due to underlying intracellular granules that store the chemicals such as heparin & histamine. Other chemicals contained in the intracellular granules include slow-reacting substance of