Preimplantation embryos consume and produce amino acids in a manner dependent upon their developmental stages,and detection of embryo metabolism may be predictive of subsequent viability.The consumption and production of amino acids by in vitro produced mouse preimplantation embryos were examined to seek for an effective amino acid composition for embryo in vitro development and optimize culture system.A total of 480 zygotes were collected from the oviducts of superovulated mice and these zygotes were cultured with KSOMaa containing Eagle’s essential amino acids and non-essential amino acids.The content of glycine,leucine,threonine,valine,phenylanine,and tyrosine in the culture medium increased at 2-cell stage,while decreased at 4-cell or 8-16 cell stages,but subsequently increased by blastocyst stage.The content of glutamic acid,methionine,arginine,and alanine decreased from 2-cell stage to blastocyst stage.The content of serine,lysine and alanine showed continuous increase during embryo development.The content of aspartic acid,proline,and tryptophan decreased at 2-cell stage,but increased in the following stages.The content of isoleucine increased at all stages except for blastocyst stage.