Effect of cysteamine and epidermal growth factor (EGF) supplementation in maturation medium on in vitro maturation, fertilization and culturing of embryos in sheep

The present study was conducted to investigate the effect of the exogenous addition of cysteamine (200 μM/ml) and epidermal growth factor (EGF; 20 ng/ml) to the maturation medium on maturation, fertilization and subsequent development of sheep oocytes, in vitro. The ovaries (n = 113) of slaughtered ewes were collected from local abattoirs in a warm normal saline solution, containing Gentamicin sulfate (50 μg/ml) in a thermos flask. The acceptable and fair quality oocytes obtained by the puncture aspiration technique were subjected to maturation in three different media viz.; for 24 h under 5% CO2 and humidified atmosphere at 38.5 °C. The matured oocytes were then subsequently subjected to fertilization using cauda epididymis spermatozoa from slaughtered rams and cultured for 6 days. The maturation percentage recorded in the EGF supplemented medium (84.9%) was significantly higher than in the cysteamine supplemented (69.6%) and control medium (67.2%). The fertilization and cleavage rates recorded were 73.7%, 49.5%, 72.3%, 52.7% and 76.5%, 55.5% in control, cysteamine and EGF supplemented media respectively. These differences were non-significant (p > 0.05). The morula formation rate recorded in the EGF supplemented (38.7%) and cysteamine supplemented (36.7%) media was significantly (p < 0.05) higher, than in the control (22.1%) medium. In conclusion, the results indicate that EGF plays an important role in the in vitro maturation and both EGF and cysteamine have a stimulatory effect on further embryonic development in sheep.