the observation that growth factor-producing cells and haemopoietic progenitor cells are not evenly distributed in the bone marrow leads us to expect that the overall effect of growth factors ( and other regulatory molecules ) on the production and function of macrophages and osteoclasts may differ when in vivo or in vitro assays are used as end-points and , in the latter case , when whole marrow or purified cell populations are tested .
C0018956
haemopoietic progenitor cells
C0007634
cell