Title: Mast cell (lung, human)
Description: Electron microscopy.
Mast cells (mastocytes) are frequently found perivascularly or perineurally. A part of this mast cell shows thin microvilli at the surface and the cytoplasm is provided with a moderate amount of organelles. At (*) the Golgi area (1) is seen in close association with granules that vary in shape and size. These membrane-bound vesicles (so-called compound granules) (2) show a metachromatic reaction in light microscopy and ultrastructurally a granule exhibits a heterogeneous content (different with species) e.g. osmiophilic granular, filamentous, whorl-like substances. These structures contain among others heparin, histamine, enzymes such as serine proteases, superoxide dismutase, b-hexosaminidase, tryptase, factors such as neutrophil – and eosinophil-chemotactic factors, vasoactive mediators, prostaglandin, leucotrien C4 and lymphokines.
Background: Analogous to basophilic granulocytes mast cells possess specific membrane receptors for the Fc segment of IgE produced in response to allergens. Eventually the release of the granular content by exocytosis (leading to degranulation of the mast cell) occurs, resulting in e.g. immediate hypersensitivity (anaphylactoid) reaction. See also POJA-L653.
Keywords/Mesh: blood, bone marrow, mast cell, basophilic granulocyte, metachromasia, histology, electron microscopy, POJA collection