The production/formation of blood cells in bone marrow is called hematopoeisis.
Blood cells begin to form at embryo stage. Blood cells are made by the red bone marrow until the age of 7 years. It means the marrow in all bones is still red at this stage. However after 7 years of age, the red bone marrow changes to yellow (inactive) as fat (yellow marrow). This fat can be seen in the long bones.
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The production/formation of blood cells in bone marrow is called hematopoeisis.
Blood cells begin to form at embryo stage. Blood cells are made by the red bone marrow until the age of 7 years. It means the marrow in all bones is still red at this stage. However after 7 years of age, the red bone marrow changes to yellow (inactive) as fat (yellow marrow). This fat can be seen in the long bones.