title: The four blastomeres of a 4-cell stage human embryo are able to develop individually into blastocysts with inner cell mass and trophectoderm.
abstract: BACKGROUND
  Early mammalian blastomeres are thought to be flexible and totipotent allowing the embryo to overcome perturbations in its organization during preimplantation development. In the past, experiments using single blastomeres from 2-, 4- and 8-cell stage mammalian embryos have provided evidence that at least some of the isolated cells can develop into healthy fertile animals and therefore are totipotent. We investigated whether isolated blastomeres of human 4-cell stage embryos could develop in vitro into blastocysts with trophectoderm (TE) and inner cell mass (ICM).
  
  
  METHODS
  Six 4-cell stage human embryos were split and the four blastomeres were cultured individually. The expression of NANOG, a marker for ICM cells, was analysed by immunocytochemistry.
  
  
  RESULTS
  The majority of the blastomere-derived embryos followed the normal pattern of development with compaction on Day 4 and cavitation on Day 5 and developed into small blastocysts with TE and ICM on Day 6 (n = 12). The four cells of one embryo were individually capable of developing into blastocysts with TE and ICM, and NANOG was expressed in the ICM.
  
  
  CONCLUSIONS
  Although based on a small number of embryos, we conclude that the blastomeres of a 4-cell stage human embryo are flexible and able to develop into blastocysts with ICM and TE.
authors.affiliation: Research Centre Reproduction and Genetics, Universitair Ziekenhuis Brussel (UZ Brussel), Laarbeeklaan 101, 1090 Brussels, Belgium. hilde.vandevelde@uzbrussel.be
authors.forename: Hilde
authors.initials: H
authors.lastname: Van de Velde
authors.forename: Greet
authors.initials: G
authors.lastname: Cauffman
authors.forename: Herman
authors.initials: H
authors.lastname: Tournaye
authors.forename: Paul
authors.initials: P
authors.lastname: Devroey
authors.forename: Inge
authors.initials: I
authors.lastname: Liebaers
mesh_terms: D001755:Blastocyst / Q000502:physiology*; D001757:Blastomeres / Q000378:metabolism / Q000502:physiology*; D046149:Embryo Culture Techniques; D004622:Embryo, Mammalian / Q000196:embryology*; D047108:Embryonic Development / Q000502:physiology*; D005307:Fertilization in Vitro; D018398:Homeodomain Proteins / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D018613:Microscopy, Confocal; D000071317:Nanog Homeobox Protein
chemical_list: D018398:Homeodomain Proteins; C486780:NANOG protein, human; D000071317:Nanog Homeobox Protein