Superovulation, fertilization and parthenogenetic activation
For superovulation, 6-week-old female mice were injected with 5 IU of pregnant mare serum gonadotropin (PMSG). After 48 h, mice were injected with 5 IU of human chorionic gonadotropin (hCG).
For fertilization, superovulated female mice were mated with adult males. Successful mating was confirmed by observation of vaginal plugs the next morning and recorded as E0.5. Embryos were harvested from ampullae of oviducts at the indicated times according to experimental need.
For parthenogenetic activation, oocytes at the MII stage were collected and treated with 5μM calcium ionophore A23187 (C7522; Sigma-Aldrich) for 5 min, then cultured in M2 medium containing10μM cycloheximide (01810; Sigma-Aldrich).