Developmental competence in vitro and in vivo of bovine IVF blastocyst after 15 years of vitrification.

BACKGROUND: It is uncertain whether long-term cryopreservation affects embryonic development. OBJECTIVE: This study was to investigate the effects of long-term cryopreservation on in vitro and in vivo developmental competence of bovine blastocysts. METHODS: The blastocysts were randomly allocated into 3 groups based on the storage time: 0.5-year group, 1-year group and 15-years group. The thawed blastocysts were subjected to in vitro culture or embryo transplantation. RESULT: Significantly lower survival rate (89.20%) and re-expansion rate (70.27%) of blastocysts were obtained from 15-years group compared with those of 0.5-year (97.50% and 87.50%) and 1-year (100.00% and 84.20%) groups (P < 0.05). There were no significant differences in the hatching rate (39.50% to 42.50%) among the three groups and the pregnancy rate between 1-year (35.00%) and 15-years (36.36%) groups. CONCLUSIONS: Although in vitro developmental competence of the 15 years cryopreserved blastocysts was decreased slightly, the pregnancy outcome was not affected.