FIGURE 1. Decreased bone volume and osteoblast functions in TNF-Tg mice.

A, femur from a 4-month-old TNF-Tg mouse and a wt littermate were fixed and processed. Paraffin-embedded sections were stained with hematoxylin and eosin. Lower bone volume in the metaphysis of the femur (green stars) is present in the TNF-Tg mouse (magnification, ×4). B, the distal femoral trabecular bone volume was measured as described previously (38). The values are the mean ± S.E. of eight or nine mice. *,p < 0.05 versus wt mice. C, bone marrow stromal cells were isolated from 4-month-old TNF-Tg mice and wt littermates and cultured in osteoblast differentiation medium containing 100 μg/ml l-ascorbic acid and 5 mm β-glycerophosphate in the presence or absence of 40 ng/ml BMP-2 for 2 weeks. The cells were fixed, and mineralized bone nodules were identified by vonKossa staining. The area of bone nodules was measured under light microscopy using point counting. The values are the mean ± S.E. of three wells. *,p < 0.05 versus wt cells. The same results were obtained from three pairs of TNF-Tg mice and wt littermates. D, mineralized bone nodules from one representative pair of TNF-Tg mice and wt littermates (magnification, ×2).