a, Mean percentage ± s.d. of metaphases with separated chromatids or diplochromosomes in IMR-90 E6E7 cells (n=3, >100 metaphases per experiment). For one-way ANOVA separated chromatids, P<0.0001; diplochromosomes, not significant. Right, representative images. b, c, Meta-TIF analysis of pre-crisis IMR-90 E6E7 cells. (b). Scatter blots show mean telomeric γ-H2AX foci ± s.e.m. on attached chromatids (n=67) or separated chromatids (n=8), ***P<0.0001, Mann-Whitney tests. (c). d, The three distinct fates of prolonged mitosis. e, f, Mean mitotic duration of prolonged mitosis associated with the indicated fate (e) and ratio of each fate after indicated duration of mitotic arrest (f) in the pre-crisis IMR-90 E6E7 cells shown in Fig. 1b. **P<0.005, Fisher's exact test. g, Cell cycle phase at cell death in pre-crisis IMR-90 E6E7 cells (left) and fate of the previous mitosis prior to death in interphase or mitosis (<2 h) (right). Scale bar, 10 µm.