Effects of 1, 2-propanediol and ethylene glycol on the development of cryopreservated 2-cell mouse embryos in uterus

Ethylene glycol (ETG) and 1, 2-propanediol (PROH) have been largely used in the cryopreservation of human and other mammalian early stage embryos due to their low toxicity and high permeability to embryos. In this study, we investigated the cryoprotective activity of ETG and PROH on the development of 2-cell embryos. Two-cell embryos were cryopresered with PROH and ETG using conventional cryopreservation procedures. After thawing, the survival rates of 2-cell embryos were assessed, and their development to 4-cell embryos, blastocysts, hatched blastocysts and offspring were compared with nonfrozen embryos. The total number of cells in a blastocyst in each group was examined. To further compare the integrity of frozen embryos between PROH and ETG, the level of cytoskeleton disruption of mouse embryos was detected. Results show that the percentage of damaged blastomeres in 2-cell mouse embryos frozen with PROH and ETG respectively showed no difference. Embryos frozen with PROH had significantly higher rates of development to 4-cell stage and expanded blastocyst stage than those frozen with ETG (82.7% vs. 64.6% and 61.2% vs. 29.1%, respectively, P<0.01). However, there was no statistical difference in hatched blastocyst rate and birth rate between PROH and ETG (32.4% vs. 32.2% and 26.9% vs. 23.5%, P>0.05). In addition, higher cytoskeleton disruption rate of embryos was observed in ETG group than in PROH group. Therefore, our results indicated that PROH does appear to be a considerable alternative to the ETG in 2-cell embryo cryopreservation in mice [Acta Zoologica Sinica 54(6): 1098–1105, 2008].