Co-culture of 1-cell mouse embryos on different cell supports.

The development of 1-cell mouse embryos in explanted oviducts, on mouse and bovine oviduct epithelial cells and on two established cell line supports is compared. The best rates of blastocyst formation were obtained using explanted oviducts; mouse and to a lesser extent, bovine oviduct epithelial cells allow good embryonic development, associated with high viability after transfer of the blastocysts obtained in co-culture. MDBK (from bovine kidney) and Vero (from Green monkey kidney) have been tested. MDBK allows high rates of blastocyst formation (67%) and the blastocysts obtained are viable. Vero does not allow the 2-cell block to be overcome. Maintenance of cell polarity for all the feeder layers did not improve embryo development. A preliminary study on the metabolic modifications induced by the feeder layers showed no modifications at all related to a decrease in glucose, an increase in lactate and early embryonic development. On the other hand, for the free amino acids, cellular supports with high embryotrophic activity seem to mimic tubal secretions, especially with a high level of glycine. Neither a genital tract origin, nor a hormonal contribution are strictly necessary for embryo co-culture, as already demonstrated by co-culture with trophoblastic tissue. Established cell lines, which are easy to handle and control, could be useful tools in embryo biotechnology.