No abstract

No abstract

No abstract

The objective of this study was to evaluate the effect of retinol (RT) and retinoic acid (RA) on the in vitro development of pre-implantation goat embryos cultured in potassium simplex optimized medium or synthetic oviduct fluid or cocultured in oviductal cells monolayer either in potassium simplex optimized medium or synthetic oviduct fluid. A total of 2407 cumulus-oocyte complexes were aspirated from 2 to 6 mm ovarian follicles from slaughtered animals. Selected cumulus-oocyte complexes were subjected to in vitro maturation in TCM 199 for 24 h at 39 °C in an atmosphere of 5% (v/v) CO(2) in humidified air. In vitro fertilization was performed in modified defined medium. Eighteen hours after in vitro fertilization, cumulus cells were removed and presumptive zygotes were randomly distributed into experimental groups. In Experiment 1, presumptive zygotes were cultured in potassium simplex optimized medium, potassium simplex optimized medium + RT, potassium simplex optimized medium + retinoic acid, synthetic oviduct fluid, synthetic oviduct fluid + RT and synthetic oviduct fluid + RA at 39 °C in a humidified atmosphere of 5% (v/v) CO(2), 5% (v/v) O(2) and 90% (v/v) N(2). In Experiment 2, presumptive zygotes were cocultured in potassium simplex optimized medium + oviductal cells monolayer, potassium simplex optimized medium + RT + oviductal cells monolayer, potassium simplex optimized medium + RA + oviductal cells monolayer, synthetic oviduct fluid + oviductal cells monolayer, synthetic oviduct fluid + RT + oviductal cells monolayer and synthetic oviduct fluid + RA + oviductal cells monolayer in an atmosphere of 5% (v/v) CO(2) in humidified air. In both experiments, media were partially changed on day 2 after in vitro fertilization and unfertilized oocytes were excluded from the experiment. Embryos were cultured or cocultured for 8 days. In Experiment 1, there was no effect of RT or RA supplementation on the proportion of oocytes that reached the morula or blastocyst stages. By contrast, Experiment 2 demonstrated that the addition of 0.28 μg/ml RT and 0.5 μm RA to the embryo culture media stimulated (p < 0.05) development to the morula and blastocyst stages under the coculture conditions tested. In conclusion, retinoids play an important role in pre-implantation development of goat embryos and can be used to enhance in vitro embryo production.

Experiments were carried out to investigate the beneficial effects of retinyl acetate (RAc) and retinoic acid (RA) on goat oocyte maturation as well as the effects of insulin-like growth factor-I (IGF-I), RAc and RA during embryo culture under chemically defined conditions. In Experiment 1, in vitro maturation (IVM) was performed in a chemically defined basic maturation medium (bMM) supplemented with 0.3 μM RAc or 0.5 μM RA. Presumptive zygotes and embryos (2-4 cells) were cultured in droplets of potassium simplex optimised medium (KSOM); however, none of the embryos reached the blastocyst stage. In Experiment 2, oocytes were matured in bMM + RAc or bMM + RA. Presumptive zygotes and 2- to 4-cell embryos were placed in fresh KSOM droplets supplemented with RAc, RA, IGF-I, RAc+IGF-I or RA+IGF-I. In Experiment 1, addition of RAc and RA to bMM increased (P < 0.05) the proportion of 2- to 4-cell embryos reaching the morula stage as compared to the control. In Experiment 2, supplementation of embryo culture media with retinoids and IGF-I increased (P < 0.05) the proportion of 2- to 4-cell stage embryos developing to the morula and blastocyst stage. Our data demonstrate that goat embryo production in chemically defined media could be improved by exogenous RAc or RA and by the interaction between retinoids and IGF-I, and that goat embryos can be produced in vitro from oocytes following protocols similar to those currently used for cattle.