Definition: Myelopoiesis is the process of proliferation, differentiation and maturation of granulocytes in the bone marrow.

• Granulocytes arise from pluripotent hematopoietic stem cells.
• PHSC differentiate into granulocyte-monocyte colony forming unit (GM-CFU). This further differentiated into granulocyte colony forming unit (G-CFU).
• G-CFU pass through successive divisions and stages and ultimately form mature granulocytes.
. Proliferation and maturation of myeloid series in the bone marrow demonstrates a continuum of development from myeloblast to the most mature granulocytes.
• Each granulocytes follow the same pattern of development i.e. myeloblast, promyelocyte, myelocyte, metamyelocyte, band cell and mature granulocytes.
• Each granulocyte can be distinguished at myelocyte stage due to the appearance of specific granules.
.During maturation, there is reduction in nucleus volume, condensation of chromatin, change in nuclear shape, appearance and disappearance of primary granules, appearance of secondary granules, color changes and change in size of the cell.
• Myeloblast, promyelocyte and myelocyte; these cells undergo mitosis and have the capability of division.
• Metamyelocytes and band cells are the components of maturation pool. These cells do not divide.
• Segmented neutrophils stored in the bone marrow and are released in the circulation.
• After few hours neutrophils marginate along with the vessel wall and is termed as marginating pool. These cells leave the circulation and enter the tissues passing through the endothelial cells by a process known as diapedesis.