Figure 2. Immunostaining showed Ihh expression in the proliferative layer (arrowhead) and the chondroblast layer (arrow) in the mandibular condylar cartilage (A) and tibia growth plate (B) of 42-day-old rats during natural growth. A significantly higher level of Ihh expression was detected in the proliferative layer of condylar cartilage during mandibular advancement (D, 7 days after experiment) than that of during natural growth (C, 42-day-old rats). Scale bars: 400 µm for A; 50 µm for B, C, and D.