Effect of EGF on the development of 16-18 celled mouse embryos and expression of EGFR after vitrification

Successful development and implantation of cryo-preserved embryos depend on suitable culture medium, cytokines, growth factors and genomic expression. Epidermal growth factor and its receptor have important roles on embryonic development and implantation. The purpose of this study was to investigate the influence of EGF on preimplantation development and to detect mRNA for the EGF receptor in vitrified mouse embryo.

8 to 16 celled mouse embryos were collected from super-ovulated NMRI mice 56 to 64 h after HCG injection and divided into 4 groups: two control groups were cultured in MEM-α (control 1) and MEM-α+EGF (10 ng/ml) as control 2. The experimental groups were vitrified immediately after collection and then cultured for 96h in MEM-α and M-α+EGF (l0 ng/ml) respectively. Expression of EGFR in hatched and hatching blastocysts was studied too. Following RT, PCR nested primers were designed to optimize the specificity.

The results showed that blastocyst formation and hatching rates were significantly lower in vitrified embryos and degeneration rate was significantly higher in these groups. Blastocyst formation, hatching and degeneration rates were not significantly different in control group 1 compared to control group 2 and also in exp. group 1 in comparison with exp. group 2. 96 hours after culture, mRNA expression of EGFR was detected in embryos in the four groups.

In conclusion addition of EGF (10 ng/ml) to a complex medium like (MEM-α) doesn’t have any stimulatory effect on embryonic development of vitrified and non-vitrified embryos. Vitrification did not prevent EGFR expression after 96h of culturing, but it seems that addition of EGF to the medium stimulates EGFR expression in mouse blastocysts.