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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.
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
situated or occurring outside any of the medullas including the medulla oblongata and the medullary cavities of the bones.
see extramedullary hematopoiesis.
the formation and development of blood cells, usually taking place in the bone marrow.
cyclic hematopoiesis of collies
see canine cyclic hematopoiesis.
a significant finding in cases of endotoxemia.
the formation of and development of blood cells outside the bone marrow, as in the spleen, liver and lymph nodes.
in embryogenesis migration of stem cells from the yolk sac blood islands sets up hematopoiesis in thymus, lymph nodes, liver and spleen. When fetal bone develops a marrow cavity hematopoiesis is similarly established. At birth hematopoiesis is largely medullary.
increased hematopoietic activity in response to a need for more cells; indicated by the presence of a higher than normal proportion of immature forms in the peripheral blood.