Fig. 1.

The ovulation and survival rates after vitrification in the oocytes from the young and aged BDF1 mice. a Young (10–14 weeks) and aged (45–54 weeks) BDF1 mice were induced to superovulate with PMSG and hCG injections, and MII oocytes were retrieved at 13 h post-hCG. The graph depicts the average number of ovulated oocytes per mouse. A total of 605 MII oocytes were retrieved from 20 young mice and 466 oocytes from 45 aged mice. The value represents mean ± S.E.M. Statistical significance was measured by a Student’s t-test (two-tailed). ***, p < 0.0001, t = 10.33, df = 63. b Viability of vitrified-warmed oocytes from young and aged BDF1 mice. A portion of MII oocytes from (a) was vitrified and stored in LN₂ for 2 to 4 weeks. The numbers were added from 8 independent experiments. The number of survived oocytes per total number of oocytes is shown within each bar. The value represents mean ± S.E.M. Statistical significance was measured by a Student’s t-test (two-tailed). **, p = 0.0022, t = 3.743, df = 14