Effect of culture systems on mouse early embryo development

The amount of oxygen available to embryos in drop cultures underparaffin may be limited by the gas mixture employed, the methodof equilibration or by the use of positive or negative pressurefiltration. When these factors were varied, in experiments usingSwiss outbred (SO) embryos, the only significant differencedetected was the poorer development of embryos from the 1-cellto blastocyst stage when cultured in medium without prior equilibration.Also under these conditions, the inclusion of glucose in themedium did not increase the incidence of 2-cell block, and glutaminein the presence of glucose enhanced the development of 1-cellembryos to blastocysts. One-cell (C57BL/6 x SJL) F₁ x SO embryoswere successfully cultured in HEPES buffered CZB medium withadded bicarbonate, under an atmosphere of air. The proportionof blastocysts formed in this medium, with a concentration of10 mM sodium bicarbonate, was not different from that developedin CZB under 5% CO₂ in air.