“…When the mitochondrial membrane potential is low, the efficiency of energy supply by oxidative phosphorylation will drop [45,51]. Cryopreservation compromises mitochondrial activity and decreases ATP concentration in mouse, bovine and human oocytes [22,49,52,53]. This present study showed the ATP concentration of vitrified porcine oocytes after 1 h thawing decreased greatly compared with that of fresh oocytes.…”