Developmental block of early embryos is due to the lack of some components in the culture medium and/or caused by inappropriate environmental conditions for embryonic development. It was shown in our experiments that the development of mouse and bovine embryos under the influence of oviducts in vitro can provide us with a model to analyze the oviductal factors that promote embryonic development. In the first experiment, it was shown that mouse zygotes developed to the blastocyst stage when a coculture system with ampulla was applied, and the duration of embryo coculture significantly affected the further development of embryos. In the second experiment, it was shown that the proportion of blastocysts of cleaved ova obtained after coculture with mouse ampulla was significantly higher than that obtained after coculture with a granulosa cell monolayer or culture without cells.