FERTILIZABILITY AND SUBSEQUENT DEVELOPMENTAL ABILITY OF BOVINE OOCYTES MATURED IN MEDIUM CONTAINING EPIDERMAL GROWTH-FACTOR (EGF)

We have previously shown that epidermal growth factor (EGF) is capable of promoting maturation of bovine cumulus-oocyte complexes in chemically defined serum-free medium. In this study, fertilizability and subsequent developmental capacity of bovine oocytes matured in EGF-containing medium were evaluated. Fetal bovine serum (FBS, 10%) and EGF at 10 ng/ml in Dulbecco's modified Eagles medium with Ham's nutrient mixture F-12 (DME/F-12) significantly increased the rate of formation of two pronuclei compared with the rate obtained from DME-F12 alone (P < 0.05). Early embryonic development was assessed during 48 h in culture. Data were evaluated in terms of cleavage and four- to eight-cell formation. Oocytes matured in 10 ng/ml EGF showed significantly higher rates of cleavage (P < 0.01) and four- to eight-cell formation than did oocytes matured in control medium (P < 0.05). Bovine oocytes matured in the presence of EGF can be normally fertilized and can cleave and develop in vitro up to the eight-cell stage.