In vitro aging of oocytes

The medium used for oocyte aging was the Chatot-Ziomek-Bavister (CZB) medium (NaCl, 81.62 mM; KCl, 4.83 mM; KH₂PO₄, 1.18 mM; MgSO₄, 1.18 mM; NaHCO₃, 25.12 mM; CaCl₂, 1.7 mM; ethylenediaminetetra-acetic acid [EDTA], 0.11 mM; glutamine, 1 mM; bovine serum albumin, 5 g/L; penicillin, 0.06 g/L; streptomycin, 0.05 g/L). After being washed three times in M2 medium and once in the aging medium, oocytes were cultured for 6 h in 100 μl of aging medium at 37.5 °C under 5% CO₂ in humidified air. At the end of in vitro aging, the oocytes were subjected to parthenogenetic activation.