Figure 1

The histologic morphology (a, b, c, d) and the expression of Col II (e, f, g, h), Col X (i, j, k, l) in the middle and posterior regions of mandibular condylar cartilage. (a, e, i) and (b, f, j) were from 4-wk male and female control subgroups (16-week-old) separately. All layers of condylar cartilage aligned regularly, with good continuity in each layer. (c, g, k) and (d, h, l) were from 4-wk male and female experimental subgroups separately. As shown in (c), thickening changes, especially in hypertrophic layer, were observed. The continuity of hypertrophic layer was interrupted by the degraded area (in the red frame near subchondral bone), in which some nuclei became eosinophilic. As shown in (d), the layers of condylar cartilage were disarranged obviously, with the continuity of hypertrophic layer interrupted. The arrow showed one hypertrophic chondrocytes island surrounded by cells from other layers. The blue ellipse showed one degraded area characterized by pyknotic, homogeneous and eosinophilic lesion with few nuclei. Near subchondral bone, there was another degraded area full of eosinophilic nuclei (in the red frame). Immunoreactivity of Col II and Col X was observed mainly in hypertrophic and mature layers of condylar cartilage. As the arrow in (h) showed, no or weak immunoreactivity was found in degraded or disarranged areas. F=fibrous layer, P=proliferating layer, M=mature layer, H=hypertrophic layer. Scale bar is 100μm in Figure1a–l, and 25μm in the enlarged red frames of Figure1c and d.