THE MAST-CELL - ORIGIN, MORPHOLOGY, DISTRIBUTION, AND FUNCTION

The mast cell remains an enigmatic cell more than 100 years after its discovery by PAUL EHRLICH at the turn of the century. It is a cell tha t is found widely distributed in the body particularly associated with connective tissues. It can be re cognised by its content of metachrom atic granules when appropriately fixed and stained with metachromatic dyes such as toulidine blue. The metachromatic granules of the mast ce ll remain an important differentiating characteristic from other cells although it is by no means absolute. In the early days of its discove ry it was thought to originate from primitive mesenchyme, thymocyte or lymphocyte. More recent evidence suggests that it may have originated from the monocyte. Current evidence points to an origin from haemopoi etic tissue in the bone marrow, the progenitors differentiate from pri mitive cells under the influence of cytokines (IL3), migrate to other body sites and then undergo differentiation and maturation under the i nfluence of growth and other factors. The mast cell has many functions exerted through its ability to produce a host of biologically active substances the most notable being heparin, serotonin, dopamine, trypta se and chymase. These substances may be released in response to immuno logical and neural stimuli. Mast cells are found to be functionally he terogenous, possibly site specific and have the ability to adapt to th eir environment, producing secretions commensurate with the needs of a ny situation. The mast cell is involved in immunological, neoplastic, inflammatory and other conditions. Much about its function has been un ravelled but there remains more to be uncovered.