A system to evaluate the quality of frozen embryos through short-term culture

The aim of the present study was to evaluate a culture system as a non-invasive approach intended for assessing the viability of recently thawed embryos prior to transfer. Embryos (n=51) were collected seven days after insemination out of 20 cows that had been treated to synchronize estrus and induce superovulation. Embryos were classified as good, fair, and poor and frozen. All embryos were cultured in McCoy medium. Morphology was monitored for a period of 24h to register the development stage every 30 min for the first 2h, and every hour thereafter. A sample of four embryos of each classification was separated at 4h, another four at 12h, and the remaining seven at 24h and the degree of apoptosis was determined for all the embryos using the TUNEL technique. Embryos of good and fair quality did not undergo major detrimental changes in development even after 7h of incubation, whereas poor quality embryos experienced changes as early as 2h after incubation. Good quality embryos invariably had fewer numbers of apoptotic cells than those of fair and poor quality suggesting that embryo culture can be a useful method to assess viability and to confirm the quality of thawed embryos previously stored in liquid nitrogen prior to transfer.