title: Expression of pro- and anti-angiogenic factors during the formation of the periocular vasculature and development of the avian cornea.
abstract: BACKGROUND
  During embryonic development, endothelial precursor cells (angioblasts) migrate relatively long distances to form the primary vascular plexus. The migratory behavior of angioblasts and localization of the primitive blood vessels is tightly regulated by pro-angiogenic and anti-angiogenic factors encountered in the embryonic environment. Despite the importance of corneal avascularity to proper vision, it is not known when avascularity is established in the developing cornea and how pro- and anti-angiogenic factors regulate this process.
  
  
  CONCLUSIONS
  Using Tg(tie1:H2B:eYFP) transgenic quail embryos to visualize fluorescently labeled angioblasts, we show that the presumptive cornea remains avascular despite the invasion of cells from the periocular region where migratory angioblasts reside and form the primary vasculature. Semiquantitative reverse transcriptase polymerase chain reaction analysis and spatiotemporal examination of gene expression revealed that pro- and anti-angiogenic factors were expressed in patterns indicating their potential roles in angioblast guidance.
  
  
  CONCLUSIONS
  Our findings show for the first time that chick corneal avascularity is established and maintained during development as the periocular vasculature forms. We also identify potential candidate pro- and anti-angiogenic factors that may play crucial roles during vascular patterning in the anterior eye.
authors: Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77025, USA.
authors: Sam
authors: S
authors: Kwiatkowski
authors: Ravi P
authors: RP
authors: Munjaal
authors: Teresa
authors: T
authors: Lee
authors: Peter Y
authors: PY
authors: Lwigale
mesh_terms: D043925:Angiogenesis Inducing Agents / Q000378:metabolism*; D000818:Animals; D030801:Animals, Genetically Modified; D001426:Bacterial Proteins / Q000378:metabolism; D003315:Cornea / Q000098:blood supply / Q000196:embryology*; D005123:Eye / Q000098:blood supply; D018507:Gene Expression Regulation, Developmental; D017403:In Situ Hybridization; D008164:Luminescent Proteins / Q000378:metabolism; D018919:Neovascularization, Physiologic; D011784:Quail / Q000196:embryology*; D013997:Time Factors; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism
chemical_list: D043925:Angiogenesis Inducing Agents; D001426:Bacterial Proteins; D008164:Luminescent Proteins; D042461:Vascular Endothelial Growth Factor A; C054562:yellow fluorescent protein, Bacteria; D040281:Vascular Endothelial Growth Factor Receptor-1; D040301:Vascular Endothelial Growth Factor Receptor-2