Absence of tetraploid neuron turnover in 1-month-old mice. A, TUNEL staining in cryosections (12 μm) from the cerebral cortex of 1-month-old mouse treated with DNase (+DNAse) or left untreated (−DNAse), immunostained with an anti-NeuN antibody, and counterstained with DAPI. B, Flow cytometric analysis of fresh cell nuclei from 1-month-old mouse cortex treated with DNase (+DNAse) (positive control), or left untreated (−DNAse), and subjected to TUNEL staining either in the presence (+TDT) or absence (−TDT) (negative control) of terminal deoxynucleotidyl transferase. Quality of cell nuclei was evaluated using DAPI counterstaining (top). C, Cryosections (12 μm) from the cerebral cortex of 1-month-old Fucci mouse immunostained with an anti-NeuN antibody and counterstained with DAPI. Nuclei labeled with geminin/mAG (Fucci), representing cells in S/G2, can be observed in the subventricular zone (arrow). Bottom, High magnifications of the dashed rectangle from the top. Cx, cortex; v, ventricle. Scale bars: A top, B, 40 μm; A bottom, C, 100 μm.