Received May 23, 2012
Accepted June 10, 2012

Objective:The maintenance of embryos is an important factor for the transport distances between them and their subsequent use. Objective: To test the viability of mouse embryos fresh and vitrified/warmed exposed at room temperature for different periods. Methods:Female mice were stimulated for two days with eGH, received hCG at the end of the second day and placed with males, after confirmation of mating, embryos were flushed from the oviduct on the third day of development and separated into six groups. Results:fresh embryos exposed to ambient temperature for 12 hours (group 2) had the same blastocyst rate (group 1). To keep the embryos for 24 hours (group 3) there was a slight decrease in viability.The vitrification process did not reduce the rate of blastocyst compared with group 1. However, by maintaining vitrified embryos for 12 or 24 hours (groups 5 and 6) the rate of blastocyst was reduced when compared to control (Group 4). When fresh or vitrified/warmed embryos were exposed to room temperature for 24 hours (groups 3 and 6), the blastocyst rate was smaller than embryos kept for 12 hours (group 2 and 5).The preservation method for short periods is adequate for the transport of fresh embryos for 12-24 hours and for embryos vitrified for 12-24 hours, even with a small reduction in blastocyst rates. Conclusion:This study shows that it is possible to keep fresh embryos for 12 hs with no loss of viability, Meanwhile, maintaining vitrified/warmed ones leads to a small loss of viability but without harming the development in vitro.