ABSTRACT
The human body consumes a staggering 400 billion mature blood cells every day, and this number increases dramatically under conditions of stress such as infection or bleeding. A complex scheme of multilineage proliferation and differentiation, termed
hematopoiesis
(Greek for blood forming), has evolved to meet this demand. This regulated production of mature blood cells from immature stem cells, which occurs mainly in the bone marrow (BM) of adult mammals, has been the focus of considerable research effort.
