Reduced vacuolation in the corpus callosum of aged Aspanur7/nur7 mice. HE staining on sagittal paraffin-embedded brain sections demonstrate a reversible phenotype in the corpus callosum of Nat8L+/+/Aspanur7/nur7 and Nat8L+/−/Aspanur7/nur7 mice. At the age of P21, Nat8L+/+/Aspanur7/nur7 (C, G) and Nat8L+/−/Aspanur7/nur7 (D, H) mice show a clear vacuolation in the white matter of corpus callosum compared with Nat8L+/+/Aspanur7/+ (control) (A) and Nat8L−/−/Aspanur7/nur7 (B) mice. At the age of 1 year, only a few small vacuoles were evident in this brain region and the histology appeared almost normal in Nat8L+/+/Aspanur7/nur7 (E, I) and Nat8L+/−/Aspanur7/nur7 (F, J) mice. Images G–J show higher magnifications of the images C–F. Scale bars: A–F, 200 μm; G–J: 100 μm.