A large bone marrow cell not usually found in the circulating blood; it is regarded as the precursors of blood platelets; it is up to 100 mm in diameter, with a polyploid nucleus. Also referred to as megacaryocyte, megalokaryocyte, and thromboblast.
An extremely large cell with an irregular lobed, ring or doughnut-shaped nucleus that stains blue-purple. The cytoplasm is abundant, light blue and is packed with fine azurophilic granules. This cell gives rise to thrombocytes.
A giant cell containing (usually) a single polyploid nucleus. The multilobed nucleus often appears to be several independent nuclei, making discrimination of these cells from osteoclasts somewhat difficult. The cell cytoplasm is somewhat granular. Megakaryoctyes are found in bone marrow where they give rise to platelets by budding.
The megakaryocyte is a bone marrow cell responsible for the production of blood platelets when its cytoplasm becomes fragmented. These fragments are blood platelets. Megakaryocytes account for less than 1% of bone marrow cells but can be 10 to 15 times larger than a typical red blood cell.(http://wikibooks.org/wiki/Biology_Cell_biology_Introduction_Cell_size Compare to other cells) DNA synthesis is occurring in the nucleus during thrombopoiesis (stimulated by thrombopoietin) without cytokenesis, aka endoreduplication.