title: Involvement of neurons and retinoic acid in lymphatic development: new insights in increased nuchal translucency.
abstract: OBJECTIVE
  Increased nuchal translucency originates from disturbed lymphatic development. Abnormal neural crest cell (NCC) migration may be involved in lymphatic development. Because both neuronal and lymphatic development share retinoic acid (RA) as a common factor, this study investigated the involvement of NCCs and RA in specific steps in lymphatic endothelial cell (LEC) differentiation and nuchal edema, which is the morphological equivalent of increased nuchal translucency.
  
  
  METHODS
  Mouse embryos in which all NCCs were fluorescently labeled (Wnt1-Cre;Rosa26(eYfp) ), reporter embryos for in vivo RA activity (DR5-luciferase) and embryos with absent (Raldh2(-/-) ) or in utero inhibition of RA signaling (BMS493) were investigated. Immunofluorescence using markers for blood vessels, lymphatic endothelium and neurons was applied. Flow cytometry was performed to measure specific LEC populations.
  
  
  RESULTS
  Cranial nerves were consistently close to the jugular lymph sac (JLS), in which NCCs were identified. In the absence of RA synthesis, enlarged JLS and nuchal edema were observed. Inhibiting RA signaling in utero resulted in a significantly higher amount of precursor-LECs at the expense of mature LECs and caused nuchal edema.
  
  
  CONCLUSIONS
  Neural crest cells are involved in lymphatic development. RA is required for differentiation into mature LECs. Blocking RA signaling in mouse embryos results in abnormal lymphatic development and nuchal edema.
authors.affiliation: Department of Obstetrics and Gynecology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Nicole B
authors.initials: NB
authors.lastname: Burger
authors.forename: Kyra E
authors.initials: KE
authors.lastname: Stuurman
authors.forename: Evelien
authors.initials: E
authors.lastname: Kok
authors.forename: Tanja
authors.initials: T
authors.lastname: Konijn
authors.forename: Dennis
authors.initials: D
authors.lastname: Schooneman
authors.forename: Karen
authors.initials: K
authors.lastname: Niederreither
authors.forename: Mark
authors.initials: M
authors.lastname: Coles
authors.forename: William W
authors.initials: WW
authors.lastname: Agace
authors.forename: Vincent M
authors.initials: VM
authors.lastname: Christoffels
authors.forename: Reina E
authors.initials: RE
authors.lastname: Mebius
authors.forename: Serge A
authors.initials: SA
authors.lastname: van de Pavert
authors.forename: Mireille N
authors.initials: MN
authors.lastname: Bekker
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D042783:Endothelial Cells / Q000166:cytology; D005260:Female; D042601:Lymphatic Vessels / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D051379:Mice; D009432:Neural Crest / Q000502:physiology*; D048208:Nuchal Translucency Measurement; D011247:Pregnancy; D014212:Tretinoin / Q000378:metabolism*
chemical_list: D014212:Tretinoin