Fig. 4

Histological observations and quantitative analyses of the articular sites of tibiae. a Representative microscopic images of toluidine blue-stained undecalcified sections. The area of metachromasia after toluidine blue staining was decreased in the CIA-vehicle group. Arrows, length of the cartilage degradation site facing the proximal end of the tibiae. Scale bars represent 500 μm and 250 μm in the upper and lower panels, respectively. b The extent of cartilage degradation = (length of cartilage degradation surface) / (total length of proximal end of tibial epiphysis, excluding anterior intercondylar area) × 100. c von Kossa-stained sections at the tibial epiphysis. d Calcified area measurements at the tibial epiphysis obtained by bone histomorphometry. Scale bar represents 1 mm. e Osteoclast number per bone surface (N.Oc/BS) at the tibial epiphysis. f Serum levels of C-terminal telopeptides of type I collagen (CTX-I) on day 49. g Serum levels of osteocalcin on day 49. Data presented as mean ± SD (n = 6). **p <0.01 vs. Normal-vehicle; ^# p <0.05, ^## p <0.01 vs. CIA-vehicle. Normal-vehicle group, nonimmunized mice receiving vehicle (20 % DMSO); CIA-vehicle group, immunized mice receiving vehicle (20 % DMSO); CIA-9 mg OP3-4 group, immunized mice receiving 9 mg/kg/day OP3-4 peptide; CIA-18 mg OP3-4 group, immunized mice receiving 18 mg/kg/day OP3-4 peptide. CIA collagen-induced arthritis