Granulopoiesis is the formation of granulocytes within the bone marrow. It is controlled by a number of substances including granulocyte colony stimulating factors.
The cell differentiation is sequentially:
- stem cell progenitor
- relatively large nucleus
- basophilic cytoplasm
- myelocytes, divided into cell lines distinguishable by granule staining within cytoplasm:
- basophilic myelocyte
- neutrophilic myelocyte
- eosinophilic myelocyte
- metamyelocyte cell lines:
- granules are becoming more concentrated within cell
- cell nucleus becomes more lobulated
- gives rise to:
- mature basophil
- mature eosinophil
- band cell
The band cell is an immature neutrophil that develops in the bone marrow by further lobulation of its nucleus.
The mature neutrophils, or band cells if a left shift has occurred, along with mature basophils and eosinophils, pass through the sinus endothelium in bone marrow through to blood.
Last reviewed 01/2018