The influences of cryoprotectants on viability of embryos produced in vitro

Background: The post-thaw embryo survival has been shown to depend on different factors such as type of cryoprotectant. Ethylene glycol, 1,2 propanediol and glycerol are among the routine cryoprotectants widely used for embryo cryopreservation in different animals and human as well. Objective: To investigate the effects of different cryoprotectants on viability of blastocysts produced in vitro and also determining a suitable cryoprotectant for embryo cryopreservation. Methods: A total of 197 porcine blastocysts produced in vitro )at days 6 and 7 post-IVF( were randomly divided into control and cryoprotectant (CP) groups. The CP groups were exposed to 10 % CP solutions (Ethylene glycol, 1,2 propanediol and glycerol) in 3 steps for 1 hr at room temperature (23-25°C). The survival rate was measured as the proportion of recovered embryos following a 24-hr culture in NCSU-37 media. The survival rate was further compared with the data obtained from the control group (cultured in 0.3% BSA in PBS with the same conditions). Findings: The results showed that the survival rates of blastocysts exposed to PD and GLY were similar to those exposed to EG (p0.05) in survival rates between the EG and control groups. Conclusion: The data indicated that the exposure of porcine blastocysts to cryoprotectant causes a reduction in survival rate and that the ethylene glycol produced the least detrimental effects