SCH 546738 in mCIA: Histopathological analysis of paws on day 9. Paws collected at day 9 from the vehicle (0.4% methylcellulose) and 40 mpk SCH 546738 groups of two independent experiments were analyzed by histopathology. (A) compares the histopathological scores of both groups of tissues. Both leukocyte infiltration into the joint and the structural damage to the bone and cartilage was significantly attenuated in SCH 546738-treated animals (* p < 0.05; ** p < 0.005, two-tailed t test). Example images of paw tissue sections collected from both groups of animals are shown in (B) (top, phalanges area; bottom, tarsal area). Massive cellular infiltrates and bone/cartilage erosions were evident in both tarsal and phalanges areas of the vehicle treated mouse paw (left panels). In contrast, cellular infiltrates were mainly observed in the phalanges region (right top), and rarely in the tarsal region (right bottom) of SCH546738-treated animals.