Figure 3.

TUNEL assays detected apoptotic cells in old mutant mice. TUNEL‐positive granule cells (stained brown in the nuclei) were observed in 21‐month‐old mutant mice (Top, middle), but not in age‐matched normal control mice (Top, left), or SkQ1‐treated 21‐month‐old mutant mice (Top, right). The nuclei were counterstained by methyl green, which is less able to stain the TUNEL‐positive nuclei. DNase I was included during the staining for positive control, which made nearly all nuclei positively stained (bottom left). Terminal deoxynucleotidyl transferase (Tdt) was omitted for negative control, where no nuclei were positive. Brownish staining outside the nuclei indicated nonspecific signals.