- A giant cell in the bone marrow that is the ancestor of blood platelets.
* * *A large cell (as much as 100 μm in diameter) with a polyploid nucleus that is usually multilobed; m.'s are normally present in bone marrow, not in the circulating blood, and give rise to blood platelets. SYN: megacaryocyte, megalokaryocyte, thromboblast. [mega- + G. karyon, nut (nucleus), + kytos, hollow vessel (cell)]
* * *mega·kary·o·cyte .meg-ə-'kar-ē-ō-.sīt n a large cell that has a lobulated nucleus, is found esp. in the bone marrow, and is the source of blood plateletsmega·kary·o·cyt·ic -ō-.sit-ik adj
* * *n.a cell in the bone marrow that produces platelet. It is large (35-160 µm in diameter), with an irregular multilobed nucleus, and with Romanowsky stains its abundant cytoplasm appears pale blue with fine reddish granules. See also thrombopoiesis.
* * *mega·karyo·cyte (meg″ə-karґe-o-sīt) [mega- + karyo- + -cyte] a giant cell 50 to 100 μm in diameter, with a greatly lobulated nucleus, found in the bone marrow; mature blood platelets are released from its cytoplasm. Called also megalokaryocyte; spelled also megacaryocyte.
Medical dictionary. 2011.