Role of Epidermal Growth Factor in Bovine Oocyte Maturation and Preimplantation Embryo Development in Vitro1

Abstract

Epidermal growth factor (EGF) has been shown to have a positive effect during in vitro maturation (IVM) and has been reported in follicular fluid at levels capable of stimulating meiosis in a variety of species. The aim of the present work was to study the effect on subsequent development of EGF present in defined medium during bovine 1) oocyte maturation or 2) embryo culture. The presence of EGF during IVM, irrespective of concentration (1, 10, 100 ng/mg), stimulated cumulus expansion and significantly increased the proportion of oocytes attaining metaphase II, the rate of cleavage, and the proportion of embryos reaching the 5- to 8-cell stage at 72 h postinsemination. Blastocyst rates on Days 7 and 9 were also significantly improved for oocytes matured in the presence of EGF (10% vs. 18-24% on Day 7 and 21% vs. 31-32% on Day 9, for Tissue Culture Medium 199 [M199] and M199 + EGF, respectively). The presence of fetal calf serum (FCS) during IVM resulted in similarly elevated rates of development. There was no cumulative effect when EGF and FCS were present together during IVM. The presence of EGF also altered the pattern of proteins neosynthesized during maturation. The maturation-promoting effect of EGF was evident for denuded oocytes also, suggesting that EGF may act, at least in part, directly on the oocyte. Immunofluorescence studies revealed the EGF receptor on immature cumulus-oocyte complexes. When present during postfertilization culture in defined medium (synthetic oviduct fluid), EGF stimulated development in comparison to that of the control but could not replace serum. The results suggest a physiological role for EGF in the regulation of bovine oocyte maturation and development.

Effect of supplementation of different growth factors in embryo culture medium with a small number of bovine embryos on in vitro embryo development and quality

“…In this sense, some authors observed no beneficial effects of EGF in the embryo CM on the blastocyst rate either in individual (mouse: O'Neill, 1997, 0.2 to 2000 ng/ ml; bovine: Keefer et al, 1994, 10 ng/ml) or in group culture (bovine: Flood et al, 1993, 10 ng/ml, Shamsuddin, 1994, 10 to 50 ng/ml, Lee and Fukui, 1995, 10 ng/ml). However, other authors observed differences both in single (mouse: Paria and Dey, 1990, 10 ng/ml; bovine: Lim et al, 2007, 10 ng/ml) and group culture (bovine: Lonergan et al, 1996, 100 ng/ml; Mtango et al, 2003, 10 ng/ml;, 5 ng/ml). On the other hand, the effect of TGF-a was also evaluated in the present work, and no beneficial effects, but rather negative, of this GF on embryo development were found, confirming results previously showed by other authors observing no beneficial effects (Brison and Schultz, 1997;Zhou et al, 2008).…”

Effect of bovine cumulus–oocyte complexes‐conditioned medium on in‐vitro maturation of canine oocytes

“…Likewise, it is possible that the growth factors may play critical roles in oocyte maturation by stimulating the pattern of proteins neosynthesized during oocyte maturation [40], and play a regulatory role in oocyte maturation in a paracrine/autocrine manner, or it might be one of the signaling factors for the resumption of meiosis in oocytes [62]. The growth factors have been shown to accelerate progression of meiosis [63] and the meiotic cell cycle in bovine oocytes, possibly by increasing H1 and MAP kinase activity during the early stages of maturation [64].…”

“…It has been reported that epidermal growth factor (EGF) stimulates the IVM of oocytes in mice [39], cattle [40], humans [41] and pigs [42]. Activin, transforming growth factor beta (TGF-b), and basic fibroblast growth factors (bFGF) have been shown to stimulate the mitotic activity of bovine granulosa cells and/or the growth of granulosa cells or follicles in culture [43,44].…”

Optimisation of in vitro culture conditions in B6CBF1 mouse embryos

“…Paraffin oil [10][11][12], mineral oil [13][14][15] and silicone oil [16,17] have been broadly used to protect culture medium from evaporation and contamination when early embryos are cultured. Further studies have indicated that the application of oil affects the embryo development either in a positive or a negative way [18,19].…”