haemopoiesis
Last reviewed 01/2018
Haemopoiesis is the process of producing cellular constituents of the blood. Haemopoietic is the associated adjective. It occurs throughout fetal and adult life to replace cells which are removed from the circulation.
In the adult, haemopoiesis occurs in bone marrow and lymphatic tissue. In the fetus, it occurs in the bone marrow and extramedullary sites: the yolk sac, liver and spleen.
Cell culture techniques indicate that all mature blood cells derive from a primitive haemopoietic stem cell precursor by ordered division and differentiation.
Haemopoiesis can be subdivided according to the type of cell being formed e.g.:
- erythropoiesis: red blood cells
- thrombopoiesis: platelets
- leucopoiesis: white blood cells
- granulopoiesis: granulocytes
Increasingly, the molecular control of haemopoiesis is becoming elucidated; haemopoietic growth factors are used clinically.