title: The role of co-culture systems on developmental competence of preimplantation mouse embryos against pH fluctuations.
abstract: OBJECTIVE
  To determine the effect of pH fluctuations of culture media, and the role of co-culture systems on embryo development.
  
  
  METHODS
  Mouse embryos were incubated in phosphate buffered solutions (PBSs) with different pH for various lengths of time. After 3 h incubation of embryos at various pH, the embryos were transferred into four media with human (HEF) and mouse (MEF) embryonic fibroblast cells, and without feeder cells; HTF and MEM-alpha. Developmental rate at day three (morula), four (expanded blastocyst) and five (hatching or hatched blastocyst) was evaluated.
  
  
  RESULTS
  Developmental rate at day three, four and five decreased when the incubation time at pH 6.2 and 8 increased to 3 h and more. In addition, significantly less embryos incubated at pH 6.2 and 8 developed to hatching and hatched blastocysts compared with pH 7.35. Embryos incubated at pH 6.2, co-cultured with MEF or HEF showed a significant improvement (P < 0.05) at day three in HEF compared to HTF, and at day five in MEF compared to HTF. At pH 8, a significant improvement (P < 0.05) was observed at day five in HEF and MEF compared to MEM-alpha.
  
  
  CONCLUSIONS
  Mouse 2-cell embryos could tolerate minor pH fluctuations, but that major pH changes affect subsequent development. Besides, feeder cells could improve embryo development, especially when embryos are prone to rise or fall in pH.
authors: Department of Anatomy, Afzalipour School of Medicine, Kerman University of Medical Sciences, 22 Bahman BLVD., Kerman, Iran. nnematollahi@kmu.ac.ir
authors: Seyed Noureddin
authors: SN
authors: Nematollahi-mahani
authors: Amirmehdi
authors: A
authors: Nematollahi-mahani
authors: Ghazaleh
authors: G
authors: Moshkdanian
authors: Zhinoosossadat
authors: Z
authors: Shahidzadehyazdi
authors: Fatemeh
authors: F
authors: Labibi
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000502:physiology*; D016009:Chi-Square Distribution; D018920:Coculture Techniques; D003584:Cytological Techniques / Q000379:methods*; D047108:Embryonic Development / Q000502:physiology*; D005260:Female; D005347:Fibroblasts / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D008297:Male; D051379:Mice; D011247:Pregnancy; D011897:Random Allocation