It is known that in vitro embryo culture lead to loss their viability. This study was designed to improve the culture medium for early development with keeping their viability. The viability was measured by continuous culture through the post-implantation stage. B6D2F1 pronucleus zygotes were collected at 22-24 hr after hCG injections and mating. Zygotes were cultured in modified HTF medium supplemented with/without NEAA (MEM non-essential amino acids solution) or MAA (MEM amino acids solution) and were observed their development. At day 4, embryos were transferred into DMEM or co-cultured with mouse fibroblasts. The embryos cultured in mHTF medium supplemented with NEAA developed to blastocyst as fast as ones in vivo. MAA also had an effect on hatching. A few pronucleus zygotes cultured in amino acids-supplemented mHTF medium and transferred into both conditions of DMEM and co-cultured with fibroblasts were developed to head fold staged embryos as well as in vivo developed blastocysts. The present study was demonstrated that suboptimal culture conditions in early development kept embryonal viability, and which lead to improve development for post-implantation.

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