Effect of epidermal and insulin-like growth factor-1 on cumulus expansion, nuclear maturation and fertilization of buffalo cumulus oocyte complexes in simple serum free media DMEM and Ham’s F-10

The object of this study was to identify the possible effects of epidermal growth factor (EGF) and insulin-like growth factor 1 (IGF-1) on cumulus expansion, nuclear maturation and fertilization of buffalo cumulus oocyte complexes (COC’s) matured and fertilized in vitro in two serum free media Dulbecco’s modified Eagles medium (DMEM) and Ham’s F-10. Oocytes were matured in vitro for 24 h either in DMEM or Ham’s F-10 with no supplements (control) or in DMEM or Ham’s F-10 media supplemented with EGF, IGF-1 or with both EGF and IGF1. After 24 h of in vitro maturation, oocytes were inseminated with sperm prepared in BO medium supplemented with 10 μg ml-1 heparin and 0.5% BSA. In Experiment 1 the proportion of oocytes showing maximum cumulus expansion was significantly higher (P<0.01) in DMEM medium supplemented with EGF plus IGF-1 at a rate of 51.2% versus the control at a rate of 18.0%. In Ham’s F-10 media a significantly higher (P<0.01) proportion of oocytes showed maximum expansion when the medium was supplemented with EGF and IGF-1 at a rate of 52.9% versus 19.4% for the control. The same oocytes, when fixed and assessed for nuclear maturation, showed that a significantly higher (P<0.01) number of oocytes had reached M-II in both DMEM and Ham’s F-10 supplemented with EGF and IGF-1 at a rate of 78.0% and 83.5% versus a rate of 43.0% and 46.3% in their respective controls. In Experiment 2, 24 h after insemination a significantly higher (P<0.01) proportion of oocytes were fertilized in both