mast cell

A mast cell (or mastocyte) is a resident cell of several types of tissues and contains many granules rich in histamine and heparin. Although best known for their role in allergy and anaphylaxis, mast cells play an important protective role as well, being intimately involved in wound healing and defense against pathogens.
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Noun
1. a large connective tissue cell that contains histamine and heparin and serotonin which are released in allergic reactions or in response to injury or inflammation
(synonym) mastocyte, labrocyte
(hypernym) somatic cell, vegetative cell
(part-holonym) connective tissue

A connective tissue cell whose normal function is unknown, the mast cell is frequently injured during allergic reactions, releasing strong chemicals including histamine into the tissues and blood that are very irritating and cause itching, swelling, and fluid leaking from cells. These allergic chemicals can also cause muscle spasm and lead to lung and throat tightening as is found in asthma and loss of voice.

A type of white blood cell.