Masson's trichrome staining of kidney sections from normal control rat (a, e), diabetic rat treated with vehicle (b, f), and a diabetic rat treated with FTY720 (c, g) or SEW2871 (d, h) at 9 weeks of the study. Representative photographs show extensive tubular damage with vacuolization (arrows), interstitial fibrosis (blue staining of interstitial collagen), and increased intertubular space (arrowhead) in vehicle-treated diabetic rats and minimal changes in treated animals. Bar = 50 μm.