Early embryonic development under oviductal influence in vitro

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The relationship between the oviduct and preimplantation embryo development in the mouse has been investigated in vitro, specifically over the period during which the oviducts affect further development. Timing of co-culture was very important. The non-species specific effects of mouse oviducts in vitro was first demonstrated in hamster embryos. Hamster early two-cell embryos maintained in organ culture of mouse oviducts could overcome the developmental arrest to some extent. Developmental competency of bovine IVM/IVF oocytes co-cultured with mouse oviductal tissue was comparable to those cultured on bovine granulosa monolayers. To investigate the effects of oviducts on the morphology of four-cell mouse embryos developed in co-culture, E-cadherin localisation was examined using monoclonal antibody ECCD-2. These developmentally competent four-cell embryos have different morphology to those developed in culture medium alone. It is suggested that the oviductal influence strongly affects the localisation of E-cadherin in the cell-cell contact region at the four-cell stage of mouse embryos. The relationship between p34 cdc2 kinase and developmental arrest at the two-cell stage was also investigated. Co-cultured and non-co-cultured embryos were collected at −1 to 26 h after first cleavage in vitro to analyse the p34 cdc2 kinase activity. The enzyme activity of co-cultured embryos collected 20–23 h after the first cleavage (late G 2 to M phase of the second cell cycle) was found to increase compared with that of non-co-cultured embryos. This suggests that the oviduct can induce the kinase activity of embryos to complete the normal cell cycle.