The effects of LIF and EGF on mouse oocyte maturation, fertilization and development in vitro

Mammalian oocytes are exposed to a mixture of many different growth factors and cytokines which provides an optimized microenvironment for oocyte maturation. In the lack of this natural microenvironment in vitro, the quality of oocyte and embryos appears to be suboptimal.

This study was undertaken to investigate the effects of EGF and LIF on in vitro maturation, fertilization and cleavage rates in mouse oocytes.

The GV oocytes were collected from female NMRI mice and randomly divided into control and 3 treatment groups. Oocytes in treatment groups were cultured in the maturation medium supplemented with 50 ng/ml rhLIF (Treatment 1), 10ng/ml EGF (Treatment 2) and 50 ng/ml LIF+ 10ng/ml EGF (Treatment 3) for 24 hours at 37°C in humidified 5% CO2 in air. The matured oocytes were fertilized in vitro and cultured for 96 hours. Finally, the developmental rates were assessed and embryos were stained using Hoechst 33258.

There was a higher maturation rate in treatment groups compared to the control group. There was not any significant difference in the rate of fertilization among the groups. The rates of cleavage (79.1%) and blastocyst formation (62.2%) were significantly higher in LIF + EGF group comparing to the other groups. The rates of hatching in groups treatment 1 (35.2%) and 3(41%) was significantly higher comparing to the other groups. Also the mean of total cell number in treatment groups significantly was higher than control (p< 0.05).

The findings of this study suggest a beneficial effect of LIF and EGF on mouse oocyte maturation and cleavage rates.