25 Interesting Facts About Human Blood

Blood Cells Originate From Stem Cells

In humans, all blood cells originate from hematopoietic stem cells. About 95 percent of the body's blood cells are produced in the bone marrow. In an adult, most of the bone marrow is concentrated in the breastbone and in the bones of the spine and pelvis. Several other organs help to regulate the production of blood cells. These include the liver and lymphatic system structures such as the lymph nodes, spleen, and thymus.