n. the process of blood *platelet production. Platelets are formed as fragments of cytoplasm shed from giant cells (*megakaryocytes) in the bone marrow by a budding process.
(haematopoiesis) n. the process of production of blood cells and platelets which continues throughout life, replacing aged cells (which are removed from the circulation). In healthy adults, haemopoiesis is confined to the *bone marrow, but in embryonic life and in early infancy, as well as in certain diseases, it may occur in other sites (extramedullary haemopoiesis). See also erythropoiesis; leucopoiesis; thrombopoiesis. —haemopoietic adj.... haemopoiesis
n. a cell in the bone marrow that produces *platelets. It is large (35–160 ?m in diameter), with an irregular multilobed nucleus, and with *Romanowsky stains its abundant cytoplasm appears pale blue with fine reddish granules. See also thrombopoiesis.... megakaryocyte
(thrombocyte) n. a disc-shaped cell structure, 1–2 ?m in diameter, that is present in the blood. With *Romanowsky stains platelets appear as fragments of pale-blue cytoplasm with a few red granules. They have several functions, all relating to the arrest of bleeding (see blood coagulation; platelet activation). There are normally 150–400 × 109 platelets per litre of blood. See also thrombopoiesis.... platelet
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