Fig. 4. Upregulation of canonical Wnt signaling in Bmpr1a cKO mice. (A) Canonical Wnt signaling assessed by TOPGAL mice using E17.5 calvariae (upper panel, lateral view; lower panel, top view). Two independent parietal bones from two littermates in each group after dissection are shown in the right-hand panel. Red arrow indicates enhanced Wnt signaling. Broken line, areas of parietal bones (P). (B) Histological analysis assessed by TOPGAL mice using E17.5 calvariae. Scale bars: 50 µm. (C) Relative cell number of DAPI and β-gal positive cells. Cells were counted in 50 fields of E17.5 calvariae from cKO (n=4) and wild type (n=4). Total cell number was obtained by counting DAPI-positive nuclei in bone. Cell number of wild type is set as 1.0. There were 2.3 times more total cells in cKO calvariae in a given section than in wild type owing to the thicker tissues, but the number of β-gal-positive cells was 19.7 times greater, resulting in an 8.5-fold increase in the proportion of β-gal positive cells in cKO mice. (D) Canonical Wnt signaling assessed by TOPGAL mice using humerus, ulna and radius at E17.5. Red arrow indicates enhanced Wnt signaling. (E) Histological analysis assessed by TOPGAL mice using radius at E17.5. Asterisks, growth plates. Scale bars: 100 µm.