Figure 1.

Spongiform vacuolation in white matter tracts of ClC-2 KO mice. A, Hematoxylin–eosin-stained brain section of a 22-month-old Clcn2 ^−/− mouse shows vacuolation in white matter tracts of the cerebellum (a), corpus callosum (b), internal capsule (c), and brainstem (d). B, An age-matched WT brain shows much less vacuolation, which is mostly attributable to capillaries. C–F, Progressive vacuolation in Clcn2 ^−/− cerebellum from P14 (C) (no vacuolation) to P28 (D), 4 months (E), and 22 months (F). G, Semithin sections of the middle cerebellar peduncle of 2-, 5-, and 14-month-old WT and ClC-2 KO mice used to quantify the area of vacuolation. Abundant vacuoles (asterisks) were visible in cerebellar white matter of 5- and 14-month-old KO but not WT animals, in which capillaries (c) are indicated. H, The white area of randomly taken sections was determined by automated image analysis and shown as the percentage of the total area [5.2 ± 0.6% (KO) vs 1.4 ± 1.3% (WT) at 2 months, 17.8 ± 0.9% (KO) vs 2.1 ± 0.5% (WT) at 5 months, and 21.3 ± 1.2% (KO) vs 3.3 ± 1.2% (WT) at 14 months; 10 sections per mouse, 3 mice each]. Error bars indicate SEM. I, Prominent vacuolation in the white matter of the spinal cord of a 14-month-old KO but not WT mouse. Scale bars: A, B, 1 mm; C–F, 0.25 mm; G, 20 μm; I, 0.5 mm.