Figure 3.

Epiphyseal growth plate chondrodystrophy in proximal tibiae of TRANCE KO (ko) and TRANCE TG/KO (tg/ko) mice. Arrowheads denote the approximate lower limit of the proliferative chondrocyte zone and arrows the lower limit of the hypertrophic zone, the distance between thus being the thickness of the hypertrophic zone. Wild-type animals (wt) show a normal growth plate, with columns of chondrocytes undergoing proliferation and differentiation to hypertrophy in the lower region, followed by remodeling of cartilage into metaphyseal bone and the formation of a marrow cavity (m). TRANCE KO animals (ko) display abnormal chondrocyte organization and differentiation, with a reduced proliferating zone (arrowhead) and a thickened zone of hypertrophy, resulting in an increase in overall thickness of the growth plate (corresponding to the dark stripe in Fig. 1 ko Inset). The TRANCE transgene failed to correct the abnormal organization and differentiation of growth plate chondrocytes, but did reduce overall growth plate thickness. Extensive amounts of mineralized cartilage (asterisks) remained unresorbed. (Original magnification, ×800.) Toluidine-blue-stained, demineralized, Epon-embedded 1-μm sections.