Prevention of 2-cell block in Kunmin mouse embryos

Aim: To investigate the efficiency of preventing 2-cell block of early embryo in Kunmin mouse in two media. Methods: M16 and CZB media containing 15% FCS or BSA were used to culture the 2-cell embryos from Kunmin mice to study their enhancement to the development of early embryos. Then, 1-cell embryos fertilized in vitro were cultured in M16 and CZB media supplemented with 15%FCS to study the ability of the medium to help 1-cell embryos from Kunmin mice to prevent the 2 cell block. And finally, glucose was added to CZB medium in different culture time to observe its effect in the development of early embryos. Results: M16 and CZB media containing 15%FCS supported optimum development from 2-cell embryos to blastocyst(78.9% and 72.7%). For 1-cell embryos fertilized in vitro , only 7.4% embryos developed to 3-4 cell embryo in M16 medium, exhibiting an obvious “2-cell block” in vitro . But in CZB medium, 72.3% embryos prevented the 2-cell block and finally 17% embryos reached blastocyst. Furthermore, when glucose was introduced into the CZB medium on the third day of the culture, the development rates of over morula and blastocyst(66.7%,28.1%) were improved significantly. Conclusion: Kunmin mouse's 1-cell embryos fertilized in vitro prevented the 2-cell block in CZB medium and developed to blastocyst. The supplement of glucose on the 3rd day of the culture improved the continuous development of embryos. [