Histology, Mast Cells

Excerpt

Mast cells are immune cells derived from the myeloid lineage. After arising in the bone marrow, progenitor cells circulate and become home to various tissues. Under the influence of stem cell factors locally produced by many cells in the tissue, the progenitor differentiates into a mature mast cell. Mature mast cells are present only in tissue and are not found in circulation.

Mast cells are found in loose (areolar) connective tissue throughout the body, in virtually every organ. They play an important role in inducing the inflammatory cascade. Innate or adaptive immune mechanisms can induce the mast cell to degranulate, releasing inflammatory mediators into the extracellular space. Mast cells are associated with many pathologies, including type I hypersensitivity reactions, mastocytosis, mast cell activation syndrome, and urticaria.