Fig. 2. Increased bone mass in Bmpr1a cKO mice. (A) Skeletal preparation of the skull and long bones at E18.5 using Alizarin Red/Alcian Blue staining. Broken line, areas of parietal bones (P). (B) Bone volume over total tissue volume (BV/TV) obtained from µCT analysis on parietal bones of the skull (left) and femur (right) at E18.5. Values are expressed as mean±s.d. (wild type, n=5; cKO, n=4, Student's t-test; ^*P<0.01). (C) Hematoxylin and Eosin staining of E18.5 calvariae. Boxed areas in frontal sections were magnified. Scale bars: 25 µm. (D) Von Kossa staining for Ca²⁺ using E18.5 calvariae. Scale bars: 25 µm. (E) Hematoxylin and Eosin staining of E18.5 humerus. Boxed areas in sagittal sections are magnified. Scale bars: 100 µm. (F) BrdU incorporation using E18.5 calvariae. BrdU-positive cells (arrows) per total cells in bone were unchanged. Scale bars: 25 µm.