Fig. 7. The effects of Zn and Zn-0.8Mg-0.2Sr on osteoclast activity, macrophage polarization, and osteogenic gene expression. (A) Tartrate-resistant acid phosphatase (TRAP) staining images. Green arrows indicate the presence of osteoclasts; (B) immunohistochemical staining of CD68, iNOS, and CD163 (n = 4); (C)–(E) present the semi-quantitative analyses of area fraction of CD68, iNOS, and CD163, respectively; (F) relative expression levels of Nos2 and Arg1 genes related to macrophage polarization (n = 4); (G) schematic illustration of the dynamic changes among M0, M1, and M2 macrophages and their corresponding markers in this study; (H) relative expression levels of Runx2, Alpl, and Bmp2 genes related to osteogenesis (n = 4). Asterisks indicate statistically significant differences (*p < 0.05, **p < 0.01, ***p < 0.001, and ****p < 0.0001).