In vivo cleavage rates and viability obtained for early cleavage mouse embryos in co-culture with oviduct cells

The cleavage rate and development of two-cell mouse embryos to the morulae stage in co-culture with mouse oviduct cells was studied in vitro and compared with those achieved in vivo. Embryos were cultured in Whittingham's T6 (T6), T6 supplemented with fetal calf serum (FCS) and in co-culture with either Dulbecco's Modified Eagles Medium supplemented with sodium lactate (DMEM + 1a) or a modification of T6 medium containing vitamins and amino acids (T6 + v + aa). Co-culture of oviductal cells with DMEM + la medium supported two-cell mouse embryo development to eight cells at a rate significantly better (P less than 0.001) than T6, but the rate of embryo development was not equivalent to that in vivo. DMEM + la alone was inadequate as an embryo culture medium. Co-cultures using T6 + v + aa with mouse oviductal cells were prepared from mice at days 1, 2 or 3 of pseudopregnancy. Day 2 and 3 co-cultures allowed two-cell embryos to develop at a rate comparable to that in vivo up to the mid eight-cell stage (68 h after hCG), but by 76 h after hCG embryos were retarded. Transfer to pseudopregnant recipients of embryos co-cultured with day 2 oviductal cells until 68 h after hCG resulted in a rate of fetal development equivalent to that of embryos grown in vivo. Our results show that co-culture of early cleavage-stage embryos with mouse oviductal cells allows embryos to retain cleavage rates and viability comparable to in vivo development.