• The effect of reducing oxygen concentration on mouse embryonic bi-cellular embryos and expression of Oct4 & Nanog genes
  • Fatemeh Soheili,1,* Mahta Moghaddam,2
    1. Islamic Azad University of Medical Sciences
    2. Alborz Medical Sciences


  • Introduction: In recent decades, assisted reproductive techniques have led to dramatic developments in the field of reproductive biology and infertility treatment. Many studies have shown that the introduction of environmental stresses affects the morphology and expression pattern of the embryo gene, and one of the goals of infertility clinics is to try to achieve culture conditions similar to those in vitro. The amount of oxygen that the embryo is in contact with during the early stages of development is one of these influential stresses. An increase in ambient oxygen levels increases the production of reactive oxygen species (ROS), which may be one of the possible reasons for the cessation of in vitro embryonic development in the two-cell stage. The use of incubators that provide less than 20% oxygen for embryo cultivation improves many quantitative and qualitative parameters such as embryo shape, viability, nesting, etc.
  • Methods: In this study, two-celled embryos after extraction were randomly divided into two groups. In the control group, embryos were cultured by applying ambient oxygen (20%) and in the treatment group, under hypoxia conditions (5% oxygen level), up to blastocyst stage. Then, in terms of cell, survival rate and exit from zona, and in terms of molecules, quantitative changes in the expression of Oct4 and Nanog genes were studied in both groups.
  • Results: The results of this study showed an increase in survival rate, exit from zona and also the expression of Oct4 and Nanog genes in the treatment group.
  • Conclusion: Environmental stress, nutrition and gas exchange during pregnancy play a very important role in the embryonic period.
  • Keywords: Blastocyst, Hypoxia, oct4 gene, Nanog