megakaryotsüüdiks

A megakaryocyte is a large, multinucleated cell found in the bone marrow. Its primary function is to produce platelets, which are essential for blood clotting. Megakaryocytes originate from hematopoietic stem cells. These stem cells undergo a series of differentiation steps, gradually increasing in size and accumulating more DNA within their nucleus, a process called endomitosis. Instead of dividing into two separate daughter cells, the chromosomes replicate, but the cell does not divide. This leads to a single, very large cell with a polyploid nucleus.

The cytoplasm of a mature megakaryocyte is filled with granules containing various factors necessary for platelet formation and function. These granules are crucial for the process of thrombopoiesis, the production of platelets. The megakaryocyte extends long, thin cytoplasmic extensions into the blood sinusoids of the bone marrow. These extensions fragment off to form proplatelets, which then break down further into individual platelets that enter the circulation. A single megakaryocyte can produce thousands of platelets. The production and maturation of megakaryocytes are regulated by hormones, particularly thrombopoietin, which is primarily produced by the liver.