Canadian Medical Guide > Biological Sciences > Biological Phenomena, Cell Phenomena, and Immunity > Cell Physiology > Cell Differentiation > Hematopoiesis Terms and Definitions

Hematopoiesis

Medical Definition:	The development and formation of various types of BLOOD CELLS. Hematopoiesis can take place in the BONE MARROW (medullary) or outside the bone marrow (HEMATOPOIESIS, EXTRAMEDULLARY).
Guide Notes:	GEN or unspecified; prefer specifics
Also Called:	Hematopoiesis, Medullary

Hematopoiesis Categories.

	Erythropoiesis - The production of red blood cells (ERYTHROCYTES). In humans, erythrocytes are produced by the YOLK SAC in the first trimester; by the liver in the second trimester; by the BONE MAROW in the third trimester and after birth. In normal individuals, the erythrocyte count in the peripheral blood remains relatively constant implying a balance between the rate of erythrocyte production and rate of destruction.
	Hematopoiesis, Extramedullary - The formation and development of blood cells outside the BONE MARROW, as in the SPLEEN; LIVER; or LYMPH NODES.
	Leukopoiesis - The process of generating white blood cells (LEUKOCYTES) from the pluripotent HEMATOPOIETIC STEM CELLS of the BONE MARROW. There are two significant pathways to generate various types of leukocytes: MYELOPOIESIS, in which leukocytes in the blood are derived from MYELOID STEM CELLS, and LYMPHOPOIESIS, in which leukocytes of the lymphatic system (LYMPHOCYTES) are generated from lymphoid stem cells.
	Thrombopoiesis - The process of generating thrombocytes (BLOOD PLATELETS) from the pluripotent HEMATOPOIETIC STEM CELLS in the BONE MARROW via the MEGAKARYOCYTES. The humoral factor with thrombopoiesis-stimulating activity is designated THROMBOPOIETIN.

Hematopoiesis Medical Definitions and Terms

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