title: Morphogenetic analysis of peri-implantation development.
abstract: BACKGROUND
  Although successful implantation is required for development in placental mammals, the molecular and morphogenetic events that define peri-implantation remain largely unexplored.
  
  
  RESULTS
  Here we present detailed morphological and immunohistochemical analysis of mouse embryos between embryonic day 3.75 and 5.25 of gestation, during the implantation process in vivo. We examined expression patterns of key transcription factors (Sox2, Oct4, Nanog, Cdx2, Gata6, Sox17, and Yy1) during pre- and postimplantation development. Additionally, we examined morphogenetic changes through analysis of ZO-1, Laminin, and E-Cadherin localization. The results presented reveal novel changes in gene expression and morphogenetic events during peri-implantation in utero. Here we show: (1) molecular and morphological changes in primitive endoderm cells as they transition from a salt and pepper distribution to a sheet covering the inner cell mass; (2) tissue-specific GATA6 levels; and (3) a striking pattern of SOX17 that is suggestive of a functional role either directing or permitting implantation at specific sites in the uterine epithelium.
  
  
  CONCLUSIONS
  A growing number of knockout mice display peri-implantation lethality, and the data presented herein identify key morphogenetic landmarks that can be used to characterize mutant phenotypes, as well as further our basic understanding of peri-implantation development.
authors.affiliation: Department of Bioengineering, University of Washington, Seattle, Washington, USA.
authors.forename: Mary C
authors.initials: MC
authors.lastname: Wallingford
authors.forename: Jesse R
authors.initials: JR
authors.lastname: Angelo
authors.forename: Jesse
authors.initials: J
authors.lastname: Mager
mesh_terms: D000818:Animals; D010064:Embryo Implantation / Q000502:physiology*; D004622:Embryo, Mammalian / Q000166:cytology / Q000378:metabolism*; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics; D014599:Uterus / Q000166:cytology / Q000378:metabolism
chemical_list: D014157:Transcription Factors
keywords: Sox17; implantation; primitive endoderm; uterine luminal epithelium