Detrimental effects of vitrification on integrin genes (α9 and β1) and in vitro fertilization in mouse oocytes

Objective Integrins are known as key molecules that importantly involve in fertilization. This study aimed to evaluate effects of vitrification on fertilization rate and expression of integrin genes, alpha 9 and beta 1, on mice oocytes in GV and M.. stages. Materials and methods From the ovarian tissue and fallopian tube of NMRI mice, germinal vesicle (GV, n = 200) and metaphase II (MII, n = 200) oocytes were obtained. Then, oocytes were distributed into 4 groups including non-vitrified GV, non-vitrified MII, vitrified GV, and vitrified MII. Cryotop method was used for vitrification and oocytes (for 4 weeks) were kept in liquid nitrogen. After that, by using an inverted microscope, the rate of survived oocytes was assessed. Also, in vitro fertilization (IVF) for oocytes, obtained from in vitro maturated MII and mice ovaries (ovulated MII), was done to assess embryos at differenced stages (2-cells, morula, and hatched). Finally, RT-qPCR was performed to investigate the mRNA expression of integrin genes (alpha 9 and beta 1). Results After vitrification, the rate of survived oocytes, 68.65%for GV and 65.07% % for MII, did not show a remarkable difference related to non-vitrified groups, while the fertilization rate in vitrified groups remarkably decrease compared to non-vitrified groups (p < 0.05). Also, the expression of alpha 9 and beta 1 genes was significantly altered in vitrified groups when compared to non-vitrified groups (p < 0.05). There was no significant difference in embryo developmental rates for non-vitrified and vitrified groups. Conclusion Cryotop method for vitrification caused an alternation in oocyte quality by reducing fertilization rate and integrin gene expression.

Automated summary

This study aimed to evaluate the effects of vitrification on fertilization rate and expression of integrin genes in mice oocytes. The results showed that vitrified oocytes had a lower fertilization rate and altered expression of integrin genes compared to non-vitrified oocytes.