Distribution of CD25⁺ cells in normal and hyperplastic MG thymi. Frozen sections of normal (A-B) and hyperplastic MG (C-E) thymi were stained with anti-CD25 mAb (red color) and counterstained with Gill hematoxylin. The left photomicrographs (original magnification × 100) show that CD25 expression is observed in the medullary area of normal (A) and hyperplastic MG thymus (C-D) and, in addition, around the germinal centers of hyperplastic MG thymus (C,E). The right photomicrographs (original magnification × 400) are enlargements of the framed areas corresponding to medullary area of normal (B) and MG (D) thymus and germinal center of MG thymus (E).