Megakaryocytic maturation occurs within the bone marrow by a process known as endomitosis. The nucleus replicates in multiples of two without cytoplasmic division, only enlargement of volume. The cytoplasm becomes less basophilic as the megakaryocyte matures, acquiring azurophilic granules. Finally, platelets are produced by fragmentation of the megakaryocyte cytoplasm. Each megakaryocyte produces some 4000 platelets, which are approximately 1 to 2 μm in diameter.

Megakaryocytic maturation is divided into three stages: the megakaryoblast, promegakaryocyte and megakaryocyte.