Myelocytes

Definition:
Myelocytes are the maturation stage of myelopoiesis between promyelocytes and metamyelocytes. They constitute 5-20% of the nucleated cells in normal bone marrow.

Appearance:

With a diameter of 15-20 µm, myelocytes are smaller than promyelocytes. The nucleus is round to oval and slightly indented on the side. Nucleoli are usually no longer visible. The cytoplasm can range in color from bluish (young forms, left picture), to "dirty" pale blue, to pale pink (right picture). Red azure granules are sporadic and may be increasingly replaced by neutrophilic secondary granules.