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mast cell n.
A cell found in connective tissue that contains numerous basophilic granules and releases substances such as heparin and histamine in response to injury or inflammation of bodily tissues. Also called labrocyte, mastocyte.
|mast cell |
A granular cell found in body tissue, especially connective tissue, that activates inflammation by releasing a variety of chemical substances including histamine, tumor necrosis factor, and interleukins. Mast cells have membrane receptors that bind to bacteria, triggering the release of inflammatory mediators from the mast cell's cytoplasmic granules. Mast cells also play an important role in allergic reactions. Other receptors on their membranes bind to specific antibodies that, combined with certain antigens, initiate granular release of chemical mediators that cause allergic signs and symptoms.
tissue cell of the immune system of vertebrate animals. Mast cells mediate inflammatory responses such as hypersensitivity and allergic reactions. They are scattered throughout the connective tissues of the body, especially beneath the surface of the skin, near blood vessels and lymphatic vessels, within nerves, throughout the respiratory system, and in the digestive and urinary tracts. Mast cells store a number of different chemical mediators-including histamine, interleukins, proteoglycans (e.g., heparin), and various enzymes-in coarse granules found throughout the cytoplasm of the cell. Upon stimulation by an allergen, the mast cells release the contents of their granules (a process called degranulation) into the surrounding tissues. The chemical mediators produce local responses characteristic of an allergic reaction, such as increased permeability of blood vessels (i.e., inflammation and swelling), contraction of smooth muscles (e.g., bronchial muscles), and increased mucus production.