Opg-independent increase of osteclastogenesis in Ctnnb1^fl/fl/LysM^+/cre mice. (A) TRAP activity staining on spine sections shows increased osteoclastogenesis in Ctnnb1^fl/fl/LysM^+/cre mice. Histomorphometric quantification of osteoclast number (Oc.N/B.Pm) and osteoclast surface (OcS/BS) is given on the right. Bars, 50 µm. (B) Concentrations of collagen degradation products (Crosslaps), Opg, and Rankl in the serum of Ctnnb1^fl/fl/LysM^+/+ and Ctnnb1^fl/fl/LysM^+/cre mice. All error bars represent mean ± SD (n = 6). Asterisks indicate statistically significant differences between the two groups. (C) qRT-PCR expression analysis of the indicated genes in marrow-flushed bones (left) or in bone marrow–derived osteoclast cultures (right) from Ctnnb1^fl/fl/LysM^+/cre mice relative to Ctnnb1^fl/fl/LysM^+/+ littermates. Error bars represent mean ± SD (n = 4). (D) Quantification of TRAP-positive multinucleated cells in Ctnnb1^fl/fl/LysM^+/+ and Ctnnb1^fl/fl/LysM^+/cre bone marrow cells differentiated by addition of M-Csf, Rankl in the absence of presence of Wnt3a, as indicated. All error bars represent mean ± SD (n = 6). Asterisks indicate statistically significant differences compared with untreated controls.