Effect of dehydroxymethylepoxyquinomicin on differentiation of osteoclasts in ankle joints of mice with collagen-induced arthritis. After taking radiographs (a-c), the ankle joints were histochemically examined for tartrate-resistant acid phosphatase-positive cells (d-i). (a), (d) and (g) Typical joint of an arthritic mouse treated with vehicle alone. (b), (e) and (h) Typical joint of an arthritic mouse treated with dehydroxymethylepoxyquinomicin. (c), (f) and (i) Joint of an age-matched normal mouse. Arrow, multinucleated giant osteoclasts.