Figure 4. Osteoclast-specific Cthrc1 KO results in a low bone mass phenotype with reduced bone formation.

(A) Design of the floxed allele of Cthrc1. (B) Comparable reduction of Cthrc1 expression in bone of ΔOC and sKO mice (generated by crossing Cthrc1^fl/fl mice with Ctsk-Cre and CAG-Cre mice, respectively). (C) Reduced 3D-determined BV relative to tissue volume (3D-BV/TV) and microstructural derangements, by μCT scanning, in ΔOC versus Cthrc1^fl/fl control mice. Representative 3D images of proximal tibia are also shown. Tb.N, trabecular number; Tb.Th, trabecular thickness; Tb.Sp, trabecular separation. Scale bars: 1 mm. n = 5. (D) Reduced bone formation parameters by histomorphometry in ΔOC mice. Osteoid surface (OS), bone formation rate (BFR), eroded surface (ES), and osteoclast surface (Oc.S) were corrected for bone surface (BS). *P < 0.05; ***P < 0.001.