Photomicrographs of CD68-immunostained sections comparing the evolution of macrophages during antigen-induced arthritis (AIA) in the presence and absence of dexamethasone (Dexa) treatment. Photomicrographs showing macrophages (20 times magnification) on sections stained with a mouse anti-rat CD68 1ry antibody and a peroxidase goat anti-mouse IgG second antibody. The slides were developed using one step AEC solution. Mayer’s hematoxylin was used as a counter staining. (A, B, C) Photomicrographs from untreated animals (control group) on days 6, 10 and 13 post-AIA induction. (D, E, F) Photomicrographs from Dexa-treated animals on days 6, 10 and 13 post-AIA induction. Red arrows indicate the edema pocket in the knee joint surrounded by inflamed synovial membrane with dense macrophage infiltration.