title: Developmental bias in cleavage-stage mouse blastomeres.
abstract: BACKGROUND
  The cleavage-stage mouse embryo is composed of superficially equivalent blastomeres that will generate both the embryonic inner cell mass (ICM) and the supportive trophectoderm (TE). However, it remains unsettled whether the contribution of each blastomere to these two lineages can be accounted for by chance. Addressing the question of blastomere cell fate may be of practical importance, because preimplantation genetic diagnosis requires removal of blastomeres from the early human embryo. To determine whether blastomere allocation to the two earliest lineages is random, we developed and utilized a recombination-mediated, noninvasive combinatorial fluorescent labeling method for embryonic lineage tracing.
  
  
  RESULTS
  When we induced recombination at cleavage stages, we observed a statistically significant bias in the contribution of the resulting labeled clones to the trophectoderm or the inner cell mass in a subset of embryos. Surprisingly, we did not find a correlation between localization of clones in the embryonic and abembryonic hemispheres of the late blastocyst and their allocation to the TE and ICM, suggesting that TE-ICM bias arises separately from embryonic-abembryonic bias. Rainbow lineage tracing also allowed us to demonstrate that the bias observed in the blastocyst persists into postimplantation stages and therefore has relevance for subsequent development.
  
  
  CONCLUSIONS
  The Rainbow transgenic mice that we describe here have allowed us to detect lineage-dependent bias in early development. They should also enable assessment of the developmental equivalence of mammalian progenitor cells in a variety of tissues.
authors.affiliation: The Howard Hughes Medical Institute, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Inna
authors.initials: I
authors.lastname: Tabansky
authors.forename: Alan
authors.initials: A
authors.lastname: Lenarcic
authors.forename: Ryan W
authors.initials: RW
authors.lastname: Draft
authors.forename: Karine
authors.initials: K
authors.lastname: Loulier
authors.forename: Derin B
authors.initials: DB
authors.lastname: Keskin
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Rosains
authors.forename: José
authors.initials: J
authors.lastname: Rivera-Feliciano
authors.forename: Jeff W
authors.initials: JW
authors.lastname: Lichtman
authors.forename: Jean
authors.initials: J
authors.lastname: Livet
authors.forename: Joel N H
authors.initials: JN
authors.lastname: Stern
authors.forename: Joshua R
authors.initials: JR
authors.lastname: Sanes
authors.forename: Kevin
authors.initials: K
authors.lastname: Eggan
mesh_terms: D000818:Animals; D001757:Blastomeres / Q000166:cytology* / Q000502:physiology; D019070:Cell Lineage; D047108:Embryonic Development; D005260:Female; D008164:Luminescent Proteins / Q000032:analysis; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D011995:Recombination, Genetic; D000097573:Red Fluorescent Protein
chemical_list: D008164:Luminescent Proteins; D000097573:Red Fluorescent Protein