81.5 MB (6.7 MB compressed)
6464 x 4406 pixels
54.6 x 37.3 cm ⏐ 21.5 x 14.7 in (300dpi)
SCIENCE SOURCE / SCIENCE PHOTO LIBRARY SCIENCE SOURCE / SCIENCE PHOTO LIBRARY
Mast cell. Coloured scanning electron micrograph (SEM) of a human mast cell. This is a leucocyte (white blood cell) that contains the chemical mediators histamine, serotonin and heparin. A mast cell is part of the immune system, and releases its contents during a localized inflammatory immune response to invading pathogens and during an allergic reaction. Histamine and serotonin cause the symptoms of allergies. Heparin is an anticoagulant which prevents abnormal clotting. Magnification unknown.
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