Fig. 3

Histomorphometric analysis of new bone regeneration via fluorochrome labeling and histological analysis. a Staining with tetracycline (column 1, yellow) after 2 weeks, alizarin red (column 2, red) after 4 weeks, and calcein (column 3, green) after 6 weeks. Column 4 shows the merged images of the three fluorochromes for the same groups (scale bar = 100 μm, white arrows indicate round shapes, high intensity, and large mass of newly formed bone in HA pores; white asterisks indicate edges of bone defect). b Percentage of each fluorochrome area in each group. c Undecalcified craniums were sliced, and sections were stained with van Gieson’s picrofuchsin. New bone and HA are shown in red and black, respectively. d New bone area in each group (*P < 0.05, versus control; #P < 0.05, versus MSC-Exos)