Fibrosis and MGCs in thymus. (A), fibrotic thymus in Apoe-/-Ctsl-/- mice. (B), foreign body type MGCs with random distribution of nuclei in Apoe-/-Ctsk-/- mice. (C), Langhans-type MGCs with horseshoe-like arrangement of nuclei in cathepsin S inhibitor treated mice. (D), cathepsin L deficiency prevents hypertrophy of thymus. (E), proportion of thymus to total body weight was significantly lower in cathepsin K- and L-deficient mice. (F), cathepsin S inhibitor treatment did not prevent thymus hypertrophy. * - p < 0.05 when compared to Apoe-/- mice. A-C, trichrome staining. (A), scale bar 130 μm, (B, C), scale bars 30 μm.