The MeOH used in the experiments was of HPLC grade and was obtained from J. T. Baker. Ultrapure water was obtained by passing redistilled water through a Direct-Q UV3 system from Millipore.

For ovary freezing, we cut ovaries from mature mice into several pieces and froze them in a cryoprotectant solution of dimethyl sulphoxide (1.5 M) and 10% fetal bovine serum in medium M2 as ...