1.1 POJA-L728. Mast cell
|
1.1 POJA-L728
Title: Mast cell Description: Scheme electron microscopy. Mast cells (mastocytes) are oval (12 mm) or spindle-shaped and are frequently found perivascularly or perineurally. The cytoplasm is provided with a moderate amount of organelles and small thin or blunt microvilli at the surface. Most obvious is the presence of large granules varying in shape and size. These membrane-bound vesicles (so-called compound granules) 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 superoxide dismutase, b-hexosaminidase, tryptase, factors such as neutrophil – and eosinophil-chemotactic factors, vasoactive mediators. |
Background:
It is considered that mastocytes arise from the bone marrow, either of a different lineage than the basophilic granulocyte or that the latter on arrival in the extravascular environment matures into a mast cell. It is also possible that extravascularly wandering hematopoetic stem cells give rise to subclasses of mast cells.
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. an immediate hypersensitivity (anaphylactoid) reaction.
Keywords/Mesh: blood, bone marrow, mast cell, basophilic granulocyte, metachromasia, histology, electron microscopy, POJA collection
It is considered that mastocytes arise from the bone marrow, either of a different lineage than the basophilic granulocyte or that the latter on arrival in the extravascular environment matures into a mast cell. It is also possible that extravascularly wandering hematopoetic stem cells give rise to subclasses of mast cells.
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. an immediate hypersensitivity (anaphylactoid) reaction.
Keywords/Mesh: blood, bone marrow, mast cell, basophilic granulocyte, metachromasia, histology, electron microscopy, POJA collection