Application of hollow fiber vitrification for cryopreservation of bovine early cleavage stage embryos and porcine morula-blastomeres

A novel hollow fiber vitrification (HFV) method was applied to materials that have previously been difficult to cryopreserve, thereby expanding the potential application of this method. The results showed that zona-free porcine morulae and their isolated blastomeres remained viable even after vitrification. The rate of development to blastocysts after vitrification was similar for zona-free and zona-intact morulae (21/23, 91.3% for both). Vitrified blastomeres had a developmental potential equal to that of non-vitrified blastomeres (blastocyst formation rate after reaggregation: 16/17, 94.1% for both). The HFV method was also effective for the cryopreservation of in vitro matured/fertilized bovine embryos at the 2- to 4-cell, 8- to 16-cell and morula stages. The blastocyst formation rates of vitrified embryos (66.1–82.5%) were similar to those of non-vitrified embryos (74.5–82.5%). These results indicate that this novel HFV method is an effective tool for embryo cryopreservation that can enhance current practices in reproductive biology.