High-power views of spleen pathology. Spleen sections from FL-overexpressing animals at 2 weeks (A and C) or 6 weeks posttransplantation (B and D) are shown. H&E-stained sections (A and C) at 2 weeks posttransplantation show splenic white pulp expanded with a polymorphous cell population (C) characterized by large, open nuclei with occasional nucleoli. Masson's trichrome-stained sections (B and D) show fibrotic (asterisk) and necrotic (star) change by 6 weeks posttransplantation. At a higher power (D), mature collagen can be seen to envelop individual cells (arrow). (A) and (B) were photographed with a 10× objective, whereas (C) and (D) were photographed with a 100× objective.