Physiology of normal bone marrow

The bone marrow is a richly innervated and highly vascularized tissue of the body responsible for hematopoiesis. The major functions include transporting oxygen, defense against foreign invasion, and hemostasis. An uncommitted pluripotent stem cell undergoes proliferation and differentiation in an orderly fashion, producing immature committed progenitors. The progenitors ultimately produce mature committed cells that are released into the circulating blood. Cell production is controlled by a variety of regulatory mechanisms, including growth factors. The availability of recombinant growth factors has stimulated clinical trials of these factors in a wide variety of hematologic diseases.