Development of bovine embryos in vitro following oocyte maturation under defined conditions

Abstract

Summary -A total of 4 615 immature bovine oocytes were used in a series of experiments aimed at the systematic evaluation of the role of the different components of our in vitro maturation (IVM) medium in imparting developmental competence to the oocytes. The results clearly demonstrate that both tissue culture medium 199 (M199) and synthetic oviduct fluid (SOF) are capable of supporting the IVM of bovine oocytes at high rates in the absence of macromolecular supplements, as evidenced by subsequent development to the blastocyst stage (20 and 25%, respectively). However, both were significantly lower than the control (containing 10% fetal calf serum, 5 pg/ml pLH (porcine luteinizing hormone), 1 wg/ml pFSH (porcine follicle-stimulating hormone), and 1 !ig/ml-17p-estradiol, E2) in terms of blastocyst yield. Inclusion of bovine serum albumin (3 mg/ml) was not beneficial and in fact significantly depressed development when added to SOF. It was shown that the advantage of the control conditions over unsupplemented M199 and SOF was entirely attributable to the presence of serum and that in the absence of serum the inclusion of the above hormone cocktail significantly depressed postcleavage development. When used individually, neither LH (50, 500, 5 000 ng/ml) nor FSH (10, 100, 1 000 ng/ml) improved development over M199 alone. In conclusion, we now have a simple maturation system, using a fully defined medium (M199) in which the search for factors improving the cytoplasmic competence acquisition of maturing cattle oocytes will be possible.

Exposure to human chorionic gonadotropin during in vitro maturation does not improve the maturation rate and developmental potential of immature oocytes from patients with polycystic ovary syndrome

“…Van Tol et al (38) found that the maturation rate did not increase when hCG was added to the maturation culture medium of bovine oocytes. The same or proximate results have been found in hamsters (26), bovines (23)(24)(25), and monkeys (39).…”

“…Many studies in animals have shown that adding hCG to culture medium may improve oocyte maturation and increase developmental potential of immature oocytes (18)(19)(20)(21), which suggests that LH/hCG is crucial for oocyte maturation and development in vitro. However, in some studies in mammalian species, adding LH/hCG into culture medium had no beneficial effect on oocyte IVM (22,23), nor did it improve subsequent embryo developmental ability in vitro (24,25). Plancha and Albertini (26) demonstrated that LH/hCG supplementation only increased the frequency of premature parthenogenesis activation and the degeneration of mature oocytes.…”

Effect of gonadotropins on oocyte maturation in vitro: an animal model

“…Many studies in animals have shown that adding hCG to culture medium improves oocyte maturation and increases the developmental potential of immature oocytes (34,(40)(41)(42)(43)(44)(45)(46), suggesting that the LH or hCG ratio is crucial for in vitro oocyte maturation and development. Other researches have demonstrated that a combination of LH and hCG added to the maturation medium will have no beneficial effects on oocyte IVM (47,48), nor the subsequent embryo developmental ability (49,50). In contrast, this research has shown improvement of porcine oocyte IVM rates with increasing concentrations of Novarel.…”

Wortmannin, A Specific Phosphatidylinositol 3-Kinase Inhibitor, Blocks In Vitro Fertilization and Embryonic Development of Bovine Oocytes Matured In Vitro with Epidermal Growth Factor.

“…This low developmental potential is attributed to a deficiency in cytoplasmic maturation [3]. Supplementing maturation medium with serum enhanced the rates of fertilization and subsequent embryonic development of bovine oocytes in vitro [4,5]. Similarly, the addition of high concentrations of gonadotropins to the maturation medium effectively increased fertilization rates, and improved rates of embryo development in vitro [1,6,7].…”