FIGURE 4:

RhoE is dispensable for primary murine OC differentiation and fusion but is required for bone resorption. (A) Micrographs showing TRAP staining of FL-OCs differentiated with M-CSF and RANKL on tissue culture–treated plates after 5, 6, and 8 d of culture. Scale bars, 200 μm. Histogram shows a time-scale quantification of the number of OCs (TRAP-positive cells with three or more nuclei) per well on tissue culture plastic and bone slices. (B) Number of nuclei per OC as indicator of OC fusion on tissue culture–treated plastic. (C) Top, micrographs and plot showing resorption index of OCs seeded for 8 d on bone. Resorbed bone is stained with toluidine blue (violet surface outline with white dotted lines). Scale bar, 200 μm. Graphs show mean ± SEM. Bottom, micrographs and plot showing resorption index of OCs seeded for 48 h on a bone-mimicking substrate (Osteo Assay plates). Unresorbed matrix is stained with silver nitrate (gray). Resorbed surface is not stained (white). Scale bar, 500 μm.