FIG. 1.

Lack of Capn4 in cells of the chondrocyte lineage reduces a proliferating but not a hypertrophic chondrocyte zone in embryonic growth plates. (A) Representative images of proximal tibia at E18.5 (left panel; Safranin O stain) and birth (right panel; hematoxylin and eosin [H&E] stain). Arrows and brackets indicate the periarticular (P) and columnar (C) proliferating, and hypertrophic (H) chondrocyte layers, respectively. The scale represents 1 μm. (B) Quantitative analysis of the length of periarticular and columnar proliferating and hypertrophic chondrocyte zones of proximal tibias at E18.5 (n = 6 in each group). The mean total length of the proliferating chondrocyte zone was shorter in mutants than in controls due to the significantly reduced length of the columnar proliferating chondrocyte layer. The lengths of the periarticular and hypertrophic chondrocyte layers were indistinguishable between mutant and control embryos. **, P < 0.005.