Representative TRAP stained histological sections of the 8th and 9th caudal vertebrae from the 0X loaded (A,B) and 6X loaded (C–F) WT (A–D), and 6X loaded TNF-Tg (E,F) mice 8 weeks after implantation are shown at 10 X and 40 X magnifications. The loaded vertebrae show a modest increase in the osteoclast numbers on the subchondral bone (C,D), which were markedly lower than that observed in loaded TNF-Tg vertebrae.