title: Effects of electric field on early preimplantation development in vitro in mice and rats.
abstract: BACKGROUND
  Exposure of cells to electric fields is a commonly used technique for parthenogenesis, cloning and tetraploid embryo production. However, little is known about possible detrimental effects of electric fields on embryos and their development. The aim of this study was to investigate the effects of electric fields on early preimplantation development in mice and rats.
  
  
  METHODS
  Mouse and rat metaphase II (MII) and pre-activated oocytes, zygotes and 2-cell stage embryos were treated with electric fields with increasing voltage. Cleavage rate, morula and blastocyst formation were evaluated by in vitro cultivation. The effects of electric fields on embryos were investigated by measurement of reactive oxygen species (ROS) content and microtubule and microfilament distributions using fluorescence staining.
  
  
  RESULTS
  Pre-activated oocytes at the pronuclear stage and zygotes are more resistant to electric exposure than freshly isolated oocytes at MII stage in both studied species. Rat zygotes treated with electric fields of increasing voltage showed higher cleavage rates compared with the mouse and some of them developed beyond 4-cell stage in vitro. Embryos blocked at the 2-cell stage after in vitro cultivation of zygotes exposed to electric fields demonstrated increased level of ROS but normal distributions of microtubules and microfilaments. In both species, embryos at the 2-cell stage were more resistant to electric fields because they formed tetraploid embryos after electric field-induced blastomere fusion and these embryos could develop in vitro until the blastocyst stage.
  
  
  CONCLUSIONS
  There are stage-dependent and species-specific differences in sensitivity to electric fields in mouse and rats.
authors.affiliation: Max-Delbrück Center for Molecular Medicine, Robert-Rössle-Str. 10, D-13125 Berlin-Buch, Germany.
authors.forename: Elena
authors.initials: E
authors.lastname: Popova
authors.forename: Michael
authors.initials: M
authors.lastname: Bader
authors.forename: Alexander
authors.initials: A
authors.lastname: Krivokharchenko
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000378:metabolism; D004477:Ectogenesis; D004558:Electric Stimulation / Q000009:adverse effects*; D046149:Embryo Culture Techniques; D005260:Female; D005818:Genetic Engineering / Q000379:methods; D007700:Kinetics; D008297:Male; D008677:Metaphase; D051379:Mice; D008810:Mice, Inbred C57BL; D009865:Oocytes / Q000378:metabolism / Q000473:pathology*; D009866:Oogenesis; D010312:Parthenogenesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D013045:Species Specificity; D015053:Zygote / Q000378:metabolism / Q000473:pathology*
chemical_list: D017382:Reactive Oxygen Species