## 3 Results and Discussion  
As shown in Figure 1, intense and homogeneous patterns of impregnation by Safranin-O were observed in the tibial articular cartilage in Group Sham along the articular surface and depth, involving typical and well-distributed chondrocytes. Group Vehicle exhibited poor impregnation, especially in the joint-wear zone. Chondrocytes were swollen, reduced in number, and irregularly distributed in the cartilage. The loss of cartilage matrix, leaving a moth-eaten appearance in the articular surface, is notorious. Group FNT10 showed \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Antigen** & **Clone** & **Dilution** & **Incubation** \\ \hline Collagen type II & 2B1.5 (Invitrogen) & 1:800 & 12 h \\ \hline IL-1\(\beta\) & AAR15G (Serotec) & 1:250 & 12 h \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Target antigens and antibodies used in the immunohistochemical study. more intense impregnation by Safranin-O than that of Group Vehicle, but not as homogeneous as that of Group Sham. A stronger intensity of staining was observed two-thirds deep into the articular cartilage, in opposition to the most superficially deep in the first-third. No morphological sign of intracellular chondrocyte edema was found in either group. The oral administration of commonetin significantly reduced the mean of cartilage-matrix-loss width (1.04 \(\pm\) 0.16 \(\upmu\)m) in comparison with Group Vehicle (1.57 \(\pm\) 0.09 \(\upmu\)m) (\(p<\) 0.01). No significant difference was observed comparing the vehicle with ibuprofen groups (1.24 \(\pm\) 0.05 \(\upmu\)m). The greatest degeneration scores were obtained in Group Vehicle (4.20 \(\pm\) 0.48), and the oral administration of commonetin significantly reduced the scores of cartilage degeneration (2.66 \(\pm\) 0.42; \(p<\) 0.05). However, no significant difference was observed comparing the group treated with ibuprofen (3.60 \(\pm\) 0.49) with the vehicle and FNT10 groups (\(p>\) 0.05). Furthermore, the treatment with commonetin (FNT10) significantly reduced the cartilage-wear depth (43.80 \(\pm\) 3.64%) in comparison with that of Group Vehicle (65.00 \(\pm\) 4.84%) (\(p<\) 0.01), which was not observed with Group Ibuprofen (45.75 \(\pm\) 1.77%) (\(p>\) 0.05). As no change in the articular surface of the joint was observed in Group Sham, this group was excluded from this quantitative analytical procedure. Figure 1: (**A**) Histological sections of the experimental groups stained with Safranin-O. Group Sham presented intense and homogeneous patterns of impregnation with Safranin-O involving typical chondrocytes (black arrows) along the articular surface (ArtS). Group Vehicle showed poor impregnation with Safranin-O, a clear loss of cartilage matrix (double-headed dotted arrow), and swollen chondrocytes (red arrows). Note the moth-eaten appearance of the articular surface. Group FNT presented a more regular appearance of the wear zone of the tibial joint surface compared with that of Group Ibuprofen. (**B**) Assessment of the mean cartilage-matrix-loss width, cartilage degeneration scores, and percentage of cartilage-wear depth in the experimental groups treated with oral administrations of vehicle only (Vehicle), formononetin at 10 mg/kg (FNT), and ibuprofen at 10 mg/kg. Differences in comparison with Vehicle are expressed as * \(p<\) 0.05 and ** \(p<\) 0.01 (ANOVA and Bonferroni’s multiplex comparison test). The pattern of immunoreactivity for the anti-collagen II antibodies, evidenced by a brown-colored matrix staining in the epiphyseal cartilage area, is shown in Figure 2. A homogeneous immunoreactivity along the articular surface, as well as along the entire length of the epiphyseal cartilage, was observed in Group Sham. Group Vehicle showed a marked reduction in the expression of collagen II, expressed as a sparse and irregular immunoreactivity pattern, limited to some focal areas of the specimens.