EFFECT OF GROWTH-FACTORS ON MORULA AND BLASTOCYST DEVELOPMENT OF IN-VITRO MATURED AND IN-VITRO FERTILIZED BOVINE OOCYTES

Growth factors were studied as a means of increasing the development of in vitro matured (IVM) and in vitro fertilized (IVF) oocytes into morulae or blastocysts. Cell numbers of blastocysts were also counted. In Experiment 1, 2- to 8-cell embryos derived from bovine IVM/IVF oocytes were randomly allotted to one of 3 culture groups: a) synthetic oviduct fluid (SOF); b) SOF + 10 ng/ml epidermal growth factor (EGF); or c) SOF + 100 ng/ml EGF; all 3 culture media contained 10% fetal bovine serum. Culture resulted in 12%, 23% and 14% (P>0.05), respectively, developing into morulae and blastocysts. In Experiment 2, 5 ng/ml of transforming growth factor beta1 (TGFbeta1) added to CR1aa medium containing BSA increased the percentage of blastocysts to 56% vs 40% for the control (P<0.05). In Experiment 3, EGF and TGFbeta1, added singly and in combination to CR1aa did not produce a synergistic effect. More embryos developed into morulae and blastocysts (45%) in a bovine oviduct epithelial co-culture than in any other treatment except in CR1aa + EGF (34%; P>0.05). In Experiment 4, 0, 1 and 5 ng/ml of platelet derived growth factor (PDGF) added to CR1aa yielded 39%, 70% and 52% morulae and blastocysts, respectively (P<0.05). Cell number was not increased, indicating that growth factors can increase the proportion of embryos that develop into morulae and blastocysts without an increase in the cell number.