Mast cell/mast cell/mast cells/Mast cells
Mast cells are roundish or spindled specialized secretory cells that contains many metachromatic granules. They are present throughout the dermis but found most commonly around blood vessels, pilosebaceous apparatus and in the subcutaneous fat (hypodermis). Their granules are rich in histamine and heparin and contains also various enzymes including eosinophil chemotactic factors of anaphylatoxis (ECF-A), neutrophil chemotactic factor (NCF), chymase, tryptase and TNF-like substance. They also produce and release prostaglandins, leukotrienes, and platelet-activating factors. Mast cells respond to physical stimuli (ligth, cold, heat, acute trauma, vibration, and sustained pressure), chemical and immunologic stimuli by releasing the content of their secretory granules. The granule release firstly induces vasodilatation, dermal edema then an infiltration into the dermis of inflammatory cells (neutrophils, eosinophils and basophils), attracted by the released chemotactic factors. Mast cells are the sentinel cell in immediate-type hypersensitivity reactions and are also involved in the production of subacute and chronic inflammatory diseases. Mastocytes stain red-violet with toluidin blue and methylene blue stains, and immunohistochemically with antibodies to chymase and tryptase. They also express the c-kit protein.
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