Fig. 3: Osteoclastogenesis in the femurs and tibias of the hamsters after SARS-CoV-2 infection.

a–c Representative TRAP staining showing the increase in the number of TRAP⁺ osteoclasts at a the distal metaphysis of the femur (n = 4), b the proximal metaphysis of the tibia (n = 4), and c the lumbar vertebrae (n = 4) after the treatment with PBS (Mock) or SARS-CoV-2 infection (4 dpi). Lower images (scale bars = 100 µm) are high-resolution versions of the boxed regions in the upper images (scale bars = 500 µm). d Corresponding quantification of TRAP⁺ osteoclasts at the trabecular bone surface after treatment with PBS (Mock, n = 4) or SARS-CoV-2 infection (4 dpi, n = 8, 30 dpi, n = 5). e Representative immunofluorescence staining images and f the corresponding fluorescence intensity quantification showing the increase in the number of TRAP⁺ NFATc1⁺ osteoclasts at the distal metaphysis of the femur at 4 dpi (n = 4). Tile scans (scale bars = 200 µm) of the distal femoral metaphysis are shown along with high-magnification of the boxed regions (scale bars = 50 µm). Data were mean ± SD. ns: P > 0.05, *P < 0.05, **P < 0.01 by one-way ANOVA with Tukey’s post hoc test (d) or two-sided Student’s t-test (f).