title: Origin of subepicardial cells in rat embryos.
abstract: BACKGROUND
  The role of the villi and vesicles of the epicardium primordium in the formation of the epicardium has been extensively studied over the last decades. With regard to the cellular contents of the villi and vesicles of the epicardium primordium, in quail the presence of mesenchymal cells in the villi recently has been described. In the present study, we have determined whether the villi and vesicles of the epicardium primordium in rat embryos contain mesenchymal cells that originate from the transverse septum and if so, whether these cells will become part of the subepicardium.
  
  
  METHODS
  Mesenchymal cells in the transverse septum of rat embryos were labelled by a method consisting of in vitro whole embryo culture and labelling of the ectoderm and its daughter cells, using wheat germ agglutinin-gold (WGA-Au) as a marker.
  
  
  RESULTS
  In concordance with our observations in the standard noncultured rat embryos, labelled cells were present in the transverse septum, extending from the umbilical ring, i.e., the transition of amniotic epithelium to ectoderm, up to the villi, in the villi and vesicles, and subepicardially.
  
  
  CONCLUSIONS
  These observations suggest that the epicardium primordium contains mesenchymal cells derived from the transverse septum. These cells reach the subepicardium, using the villi and vesicles of the epicardium primordium as their vehicle.
authors.affiliation: Department of Clinical Genetics, Erasmus University Medical School, Rotterdam, The Netherlands.
authors.forename: S M
authors.initials: SM
authors.lastname: Van den Eijnde
authors.forename: A C
authors.initials: AC
authors.lastname: Wenink
authors.forename: C
authors.initials: C
authors.lastname: Vermeij-Keers
mesh_terms: D000818:Animals; D046508:Culture Techniques; D005314:Embryonic and Fetal Development / Q000502:physiology; D005260:Female; D005318:Fetal Heart / Q000166:cytology / Q000196:embryology*; D006325:Heart Atria / Q000166:cytology / Q000196:embryology; D008648:Mesoderm / Q000166:cytology*; D010496:Pericardium / Q000166:cytology / Q000196:embryology*; D051381:Rats; D014909:Wheat Germ Agglutinins / Q000032:analysis
chemical_list: D014909:Wheat Germ Agglutinins