Effects of myo-inositol on oocyte and early embryo development in Tibetan sheep

Myo-inositol (MYO) is an essential compound within the ovarian follicular microenvironment, which facilitates the transmission of follicle-stimulating hormone signals in oocytes, thereby aiding in their maturation. Metabolomics analysis of follicular fluid from Tibetan sheep and in vitro maturation experiments have revealed the presence of myo-inositol; however, it remains uncertain whether the administration of exogenous myo-inositol can effectively enhance the maturation of Tibetan sheep oocytes. Consequently, this study was designed to explore the effects of myo-inositol supplementation on oocyte maturation and early embryo development. The influence of myo-inositol on oocyte quality was measured through various parameters, including reactive oxygen species, glutathione levels, mitochondrial function, mitochondrial membrane potential, and calcium ion concentration. The findings showed that 25 mM MYO markedly boosted the maturation rate of Tibetan sheep oocytes, significantly lowered oxygen radical formation, and increased glutathione, calcium ion concentration, and endoplasmic reticulum activity. The addition of 25 mM MYO to the in vitro embryo culture medium also substantially enhanced blastocyst formation. In summary, this study demonstrated that myo-inositol supplementation can improve both the rate of maturation of Tibetan sheep oocytes and the development of early embryos. This research lays a foundational framework for enhancing the in vitro maturation system of Tibetan sheep oocytes and the overall efficiency of in vitro embryo production.