Fig. 1. Hdac3 ablation in chondrocytes during postnatal growth delays skeletal development.
(A) Immunohistochemistry for HDAC3 on tibial growth plates of 4-week-old Hdac3-CKOCol2ERT mice that had been injected with tamoxifen or vehicle at P5. Scale bars, 200 μm. (B) qPCR for Hdac3 in the xiphoid processes of 8-week-old mice described in (A) (n = 3 mice per group). (C) Weights of male mice at indicated ages (n = 5 mice per group). (D) Femur lengths of 8-week-old male animals described in (A) were measured in micro-CT (computed tomography) scans (n = 5 mice per group). (E) Alcian blue/eosin-stained tibial sections isolated at the indicated ages from mice described in (A). Scale bars, 100 μm. (F) Quantification of SOC area to total tissue area of epiphyses from 2-week-old Hdac3-CKOCol2ERT or C57BL/6 mice injected at P5 with tamoxifen or vehicle (n = 5 mice per group). N.S., not significant. (G) Quantification of total growth plate (GP) depth across the indicated regions in 4-week-old animals described in (A) (n = 5 mice per group). (H) Equilibrium partitioning of an ionic contrast agent (EPIC)–CT scans of femoral condyles from 4-week-old mice described in (A) (top). The yellow arrow points to residual cartilage along the growth plate in the Hdac3-CKOCol2ERT mice. Three-dimensional reconstructions of the femoral condyles show the growth plate (solid gray) within the bone architecture (semitransparent blue). A, anterior; D, dorsal; L, lateral; M, medial; P, posterior; V, ventral axes. (I) Immunohistochemistry for phosphorylated γH2A.X on tibiae of 2- and 4-week-old mice described in (A). Scale bars, 100 μm. (J) Immunohistochemistry for PECAM-1 on tibiae of P9 pups described in (A). Scale bars, 100 μm. *P = 0.05, #P = 0.075, Student’s t test.