EFFECT OF CULTURE SYSTEMS ON MOUSE EARLY EMBRYO DEVELOPMENT

The amount of oxygen available to embryos in drop cultures under paraf fin may be limited by the gas mixture employed, the method of equilibr ation or by the use of positive or negative pressure filtration. When these factors were varied, in experiments using Swiss outbred (SO) emb ryos, the only significant difference detected was the poorer developm ent of embryos from the 1-cell to blastocyst stage when cultured in me dium without prior equilibration. Also under these conditions, the inc lusion of glucose in the medium did not increase the incidence of 2-ce ll block, and glutamine in the presence of glucose enhanced the develo pment of 1-cell embryos to blastocysts. One-cell (C57BL/6 x SJL) F1 x SO embryos were successfully cultured in HEPES buffered CZB medium wit h added bicarbonate, under an atmosphere of air. The proportion of bla stocysts formed in this medium, with a concentration of 10 mM sodium b icarbonate, was not different from that developed in CZB under 5% CO2 in air.