Effect of lecithin on in vitro and in vivo survival of in vitro-produced bovine blastocysts after cryopreservation

摘要

In experiment 1, blastocysts were equilibrated in cryoprotectant solutions without cooling. Cryoprotectant was diluted from embryos with 0.5 and 0.2 M sucrose. The percentages of fully expanded and hatched blastocysts treated with or without soyabean lecithin after 24 and 48 h in culture were similar (100 vs. 100% and 93.3 vs. 100% respectively). In experiment 2, the in vitro survival of frozen-thawed in vitro-matured, fertilized and cultured (IVMFC) blastocysts was compared when cryoprotectant solutions were supplemented with or without lecithin. No significant effect of lecithin was found on the ability of frozen-thawed blastocysts to re-expand after 48 h in culture (65.6 and 54.2% respectively). However, the post-thaw hatching rate of embryos cryopreserved in the presence of 0.1% lecithin was significantly higher after 72 h in culture (52 and 31.8% respectively). In experiment 3, the ability of frozen-thawed IVMFC blastocysts to establish pregnancy following single embryo transfer was determined. Transfers of 58 and 66 frozen-thawed embryos cryopreserved with or without lecithin resulted in 6 and 10 (10.3 and 15.1% respectively) confirmed pregnancies at day 60. It is concluded that addition of lecithin to cryoprotectants does not improve thein vivo development rate of cryopreserved IVMFC bovine blastocysts.