Data are presented as mean ± standard error (n = 6 animals/group). SIH: sham intermittent hypoxia group; IH-35: intermittent hypoxia for 35 days. a, Damage index: can range from 0 (completely undamaged, 100 cells × 0) to 400 (with maximum damage, 100 × 4). b, Damage frequency: calculated based on the number of cells with tails versus those with no tail. **, p < 0.01, statistically significant difference from sham intermittent hypoxia group (t-test).