In vitro production of bovine embryos has become a routine, increasingly available technology. Presently this technique can yield approximately 40% of blastocysts in relation to the number of oocytes used for in vitro maturation and fertilization. However, available data indicate that in vitro produced bovine embryos are more susceptible to freezing and subject to a higher incidence of fetal loss following transfer. The comparison between in vivo (sheep oviducts) and in vitro (co-culture with somatic cells) embryo culture conditions revealed that in vivo conditions are superior in terms of quality of embryos. The factors influencing quantity and quality of in vitro produced embryos, i.e. the size of ovarian follicle for immature oocytes recovery, methods of oocytes recovery, morphology of immature oocytes, bull effect on IVF and possible ways to overcome these limitations as well as the effect of different embryo culture systems have been discussed.
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L.Katska, Zaklad Fizjologii Rozrodu Zwierzat, Instytut Zootechniki, 32-083 Balice k. Krakowa, Poland, e-mail: firstname.lastname@example.org