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the formation and development of blood cells. In the embryo and fetus it takes place in a variety of sites including the liver, spleen, thymus, lymph nodes, and bone marrow; from birth throughout the rest of life it is mainly in the bone marrow with a small amount occurring in lymph nodes. Called also hematogenesis, hemogenesis, and hemopoiesis.
extramedullary hematopoiesis the formation and development of blood cells outside the bone marrow, as in the spleen, liver, and lymph nodes.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
The production of blood cells in tissues other than bone marrow, e.g., in the liver or spleen. It occurs in severe or chronic anemias and other diseases that affect blood cell formation. Synonym: myeloid metaplasia
See also: hematopoiesis
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