title: Gastrulating chick embryo as a model for evaluating teratogenicity: a comparison of three approaches.
abstract: BACKGROUND
  Teratology studies must be carefully designed to minimize potential secondary effects of vehicle and delivery routes. A systematic method to evaluate chick models of early embryogenesis is lacking.
  
  
  METHODS
  We investigated 3 experimental approaches that are popular for studies of early avian development, in terms of their utility for teratogen assessment starting at gastrulation. These included in vitro embryo culture, egg windowing followed by direct application of a carrier vehicle to the embryo, and injection of a carrier vehicle into the egg yolk. We also developed a morphologically based scoring system to assess development of the early embryo.
  
  
  RESULTS
  The in vitro culture and egg windowing approaches both caused an unacceptably high incidence of central nervous system and cardiac abnormalities in vehicle-treated embryos, which made it difficult to identify teratogen-specific defects. In contrast, exposing chick embryos to vehicle via direct egg yolk injection did not induce developmental anomalies.
  
  
  CONCLUSIONS
  Optimization of the exposure route of potential toxicants to the embryo is critical because control treatments can cause developmental anomalies. In ovo yolk injection minimizes perturbation of young embryos and may be appropriate for teratogen delivery.
authors.affiliation: Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: Victoria J
authors.initials: VJ
authors.lastname: Drake
authors.forename: Stacy L
authors.initials: SL
authors.lastname: Koprowski
authors.forename: John W
authors.initials: JW
authors.lastname: Lough
authors.forename: Susan M
authors.initials: SM
authors.lastname: Smith
mesh_terms: D000818:Animals; D002642:Chick Embryo / Q000002:abnormalities* / Q000187:drug effects*; D004353:Drug Evaluation, Preclinical / Q000379:methods; D005775:Gastrula; D008954:Models, Biological; D013723:Teratogens / Q000633:toxicity*; D018600:Teratology / Q000379:methods*
chemical_list: D013723:Teratogens