title: Sonographic, stereological and Doppler flow velocimetric assessments of placental maturity.
abstract: OBJECTIVE
  To determine whether sonographic assessments of increasing placental maturity are associated with changes in the theoretical diffusing capacity of the organ and with changes in vascular resistance.
  
  
  METHODS
  Placental maturity was assessed sonographically in 10 organs: five were classified as completely immature and five as completely mature. Doppler flow velocimetric recordings were obtained shortly before delivery performed by elective caesarean section. Placental biopsies taken immediately after delivery were analysed stereologically.
  
  
  RESULTS
  No differences were observed in either placental weight or volume, but the morphometric diffusing capacity of the villous membrane was 40% higher in the mature than in the immature placentas. Doppler indices did not alter with increasing placental maturity.
  
  
  CONCLUSIONS
  Normal term placentas differ significantly in their diffusion characteristics, even when organ weight and volume remain constant. Umbilical vascular resistance may be heavily influenced by the number of parallel circulatory units offered by the placental lobules.
authors.affiliation: Department of Anatomy, University of Cambridge, UK.
authors.forename: G J
authors.initials: GJ
authors.lastname: Burton
authors.forename: E
authors.initials: E
authors.lastname: Jauniaux
mesh_terms: D001783:Blood Flow Velocity; D002196:Capillaries / Q000033:anatomy & histology; D002824:Chorionic Villi / Q000033:anatomy & histology; D005314:Embryonic and Fetal Development; D005260:Female; D006801:Humans; D017078:Laser-Doppler Flowmetry; D009929:Organ Size; D010920:Placenta / Q000033:anatomy & histology* / Q000098:blood supply / Q000000981:diagnostic imaging; D011247:Pregnancy; D014463:Ultrasonography