define mast cell
(Science: cell biology, immunology) resident cell of connective tissue that contains many granules rich in histamine and heparan sulphate. release of histamine from mast cells is responsible for the immediate reddening of the skin in a weal and flare response. Very similar to basophils and possibly derived from the same stem cells. two types of mast cells are now recognised, those from connective tissue and a distinct set of mucosal mast cells, the activities of the latter are T-cell dependent.