Blastocyst rate and live births from vitrification and slow-cooled two-cell mouse embryos.

Objective: The purpose of this study was to develop a closed vitrification system, compare vitrification to a slow-cooled cryopreservation method, and compare the pup rate between both methods using two-cell mouse embryos.

Design: Randomized, prospective animal study.

Setting: Hospital-based IVF practice.

Animal(s): B6C3F1 mouse embryos.

Intervention(s): Two-cell mouse embryos were cryopreserved using a slow-cooled or vitrification method and then thawed at a later date. The embryos were cultured and transferred to recipient females.

Main Outcome Measure(s): Embryos were observed for blastocyst rate and pups were observed for phenotypic anomalies and weighed at 30, 60, and 90 days after birth.

Result(s): Neither the blastocyst rate, pup rate, nor pup weights were significantly different when the two cryopreservation methods were compared.

Conclusion(s): Because there were no differences in blastocyst rates, pup rates, or pup weights, we plan to further investigate the potential effects of vitrification on genotypic damage via the Comet Assay.