Effect of time of the addition of glucose to a medium on the development of 1-cell stage mouse embryos

In the present study, 1‐cell stage mouse embryos were cultured with or without glucose, and their development to the blastocyst stage was compared. Embryos cultured in a glucose‐free medium had a higher percentage of development to the 8‐cell stage, and they had higher developmental speeds compared with those cultured in a glucose‐containing medium. The percentages of embryos that developed to the early blastocyst stage, blastocyst stage and expanded blastocyst stage were much lower than those developed in a glucose‐containing medium. This suggests that the culture of 1‐cell stage embryos in a glucose‐containing medium inhibits development at the 8‐cell stage, and that glucose is necessary for blastocyst formation. Previous reports indicate that, from the 1‐cell stage to the 4‐cell stage, glucose inhibits embryo development. In the present study, exposure of early embryos to a glucose‐free medium improved subsequent embryo development, and there was no difference in the percentage of development to the stages ranging from the 8‐cell stage to the expanded blastocyst stage between embryos cultured in a glucose‐free medium from the 1‐cell stage to the 2‐cell, 4‐cell and 8‐cell stage. This indicates that embryo development is improved when a 1‐cell stage embryo is exposed to a glucose‐free medium before and during the 2‐cell stage, and glucose only has an inhibitory effect on embryo development during conversion from the 1‐cell stage to the 2‐cell stage.