Figure 4. β-catenin mutant growth plates have normal tissue architecture and delayed maturation.

Sections of 18.5 dpc distal femur were stained with Masson’s Trichrome (A) or processed for in situ hybridization (B; Prelp, Ihh, ColX) or for immunofluorescence (B; cleaved caspase 3). (A). β-catenin mutant cartilage shows similar cellular architecture to wild type in all maturation zones. Differences in chondrocyte density between wild type and mutant samples were noted. (B) Mutant chondrocytes transit through normal phases of maturation indicated by expression of Prelp (proliferative zone), Ihh (prehypertrophic zone), and ColX (hypertrophic zone). Cleaved caspase 3 antibody staining shows an increase in apoptotic cells in hypertrophic chondrocytes of β-catenin mutant growth plates. (C) In β-catenin mutant growth plates, the resting zone is significantly longer (measurement denoted with red bracket) and the prehypertrophic and hypertrophic zones are slightly longer than in wild type embryos. In contrast, the proliferative zone is shorter in mutants than in wild type embryos (n=5). Data are reported as a ratio of the zone length to the total growth plate length. Scale bar equals 200 µm in low magnification panels in (A) and all panels in (B). Scale bar equals 100 µm in high magnification panels in (A).