Figure 1

Osteoclast formation from human PBMCs. PBMCs were incubated with M-CSF and RANKL on bone slices for 7 days. Sample bone slices were taken and stained with toluidine blue (A, B) to assess multinuclear cell formation and bone resorption (bar = 100 μm). In A, virtually all of the cells shown are multinuclear, with only a very occasional cell (white arrows) remaining mononuclear. B: at higher magnification many excavations (black arrows) can be visualized as darkly-staining areas beneath the osteoclasts. C: SEM of bone slice after removal of cells. Almost the entire surface shows excavation, with only occasional islands of unresorbed surface remaining.