51.2 MB (3.5 MB compressed)
4370 x 4095 pixels
37.1 x 34.8 cm ⏐ 14.6 x 13.7 in (300dpi)
NIBSC / SCIENCE PHOTO LIBRARY NIBSC / SCIENCE PHOTO LIBRARY
False-colour scanning electron micrograph (SEM) of unactivated blood platelets on the surface of endothelium. Platelets, or thrombocytes, are small, non-nucleated cells formed in the bone marrow. They occur in circulating blood in large numbers. In an unactivated state they are shaped like round or oval wafers 2-3 micrometres in diameter; activated platelets (see photo P256/013) have dendritic processes. Platelets function in 2 ways: they help plug small defects in the walls of small blood vessels; & they are involved in blood clotting & in the release of serotonin, which reduces blood flow by constricting damaged vessels. Magnification: x4800 at 6x4.5cm size.
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