Effects of glucose and fructose on fertilization, cleavage, and viability of mouse embryos in vitro.

In this study we examined the role of glucose, and the use of fructose as a replacement, in embryo culture medium. Three embryo culture media were used: a routine embryo culture medium (M16), M16 without glucose (M16-G) and M16-G supplemented with fructose (M16F-G). Their effect on fertilization, rate of cleavage, and embryo viability were examined in both an outbred (OF1) and an inbred (C57Bl) mouse strain. Of the three media, only M16 was found to support fertilization. In vitro-fertilized embryos from OF1 oocytes and C57Bl oocytes and OF1 sperm were placed in the different media at the early 2-cell stage. In 65% of OF1 embryos cultured in M16, development was blocked at the 2-cell stage, whereas in M16-G and M16F-G embryos, only 22% and 32%, respectively, were blocked. M16F-G medium also produced morulae and blastocysts with higher cell numbers than M16-G. In vitro-fertilized C57Bl 2-cell embryos cultured in M16 displayed retarded cleavage to the 4-cell stage compared to embryos cultured in M16-G and M16F-G. In contrast, the morulae and blastocyst cell numbers were significantly lower in M16-G compared to M16 and M16F-G. The viability of morulae and blastocysts obtained from OF1 and C57Bl embryos cultured in M16-G and M16F-G was lower compared to control C57Bl morulae and blastocysts cultured in M16. The results show that although morphologically normal embryos could be obtained in M16-G and M16F-G, inherent anomalies existed that limited viability.