Embryo production

Researchers and technicians have developed several protocols for the production of embryos both in vitro and in vivo to be used both in animal breeding to increase the number of superior genotypes, and as a research tool. In vivo embryo production by Multiple Ovulation and Embryo Transfer (MOET) still accounts for the majority of embryos produced worldwide, but it has high costs and the number of produced embryos is often highly variable and unpredictable because of the donor effect. The application of MOET technologies requires the selection of valuable donors in perfect gynecological conditions and the administration of a superovulatory treatment to increase the number of growing follicles. Embryos are generally recovered 6-7 days after the induction of ovulation and either transferred to synchronized recipients or frozen. In vitro embryo production (IVP) is a newer and more flexible approach, although it requires specific laboratory expertise and equipment. Oocytes can be obtained both from ovaries collected at the slaughterhouse or from live donors by follicle aspiration. Cumulus-oocyte complexes are then selected and processed in vitro for embryo production. This technology involves three major steps, oocyte maturation, fertilization and embryo culture up to the blastocyst stage, which require different culture media and incubation conditions. The goal of increasing efficiency of in vitro embryo production has been the driving force for much of the applied research in embryo biology and culture. Yet, in vivo produced embryos are still of higher quality, as evidenced by higher implantation rates after transfer and cryosurvival.