Hollow fiber vitrification allows cryopreservation of embryos with compromised cryotolerance

Purpose This study aims to demonstrate vitrification methods that provide reliable cryopreservation for embryos with compromised cryotolerance. Methods Two‐cell stage mouse embryos and in vitro produced porcine embryos were vitrified using the hollow fiber vitrification (HFV) and Cryotop (CT) methods. The performance of these two methods was compared by the viability of the vitrified‐rewarmed embryos. Results Regardless of the method used, 100% of the mouse 2‐cell embryos developed successfully after vitrification‐rewarming into the blastocyst stage, whereas vitrification tests using porcine morulae with the HFV method produced significantly better results. The developmental rates of vitrified porcine morula into the blastocyst stage, as well as blastocyst cell number, were 90.3% and 112.3 ± 6.9 in the HFV group compared with 63.4% and 89.5 ± 8.1 in the CT group (P