In 1868, Ernst Neumann recognized that blood cells re- quire continuous replenishment during postnata1life. Before him, the assumption was that cells of the blood, like nerves once formed in the embryo, remain in the body throughout life. Neumann also recognized that this process occurred within the bone marrow, because this tissue provided a fa- vorable environment for proliferation and differentiation of blood cell precursors. Vera Danchakoff, the Russian embryologist working in the US, in 1916 made an analogy to the soil and the seed. Bone marrow forms the soil, providing a favorable...

Perhaps no scientific field in recent years has gained in techniques and applications as much as molecular biology, and it is certainly no ex- aggeration to-say that among all the applications of molecular biology, hematology in general, and hemopoiesis in particular, have benefited most. Owing to the applications of molecular biology, we now live in a golden era of hemopoiesis. Our understanding of the intricate regulatory system in hemopoiesis has vastly expanded. The potential for future exploration is ever expanding, and finally, the possibility of gene manipulation, has provided the...