Figure 2. Cellular response of condylar cartilage during adaptive remodeling triggered by mandibular protrusion (Sprague-Dawley rats at 56 days of age, with 21 days of mandibular advancement). The enhanced chondrogenesis results in increased thickness of the proliferative zone (P). The accelerated transition from chondrogenesis to osteogenesis is taking place in the erosive zone (E), where hypertrophic chondrocytes and surrounding matrices are degenerated and are replaced by the advent of endochondral bone formation (H&E, Bar = 10 µm).