title: Comparison of the configuration of the posterior bifurcation of the posterior communicating artery between fetal and adult brains: A study of a Sri Lankan population.
abstract: OBJECTIVE
  The purpose of this study was to examine the degree of contribution from the vertebrobasilar and carotid systems to the origin of the PCA in fetal autopsy brains of last trimester of pregnancy and to compare with published data on the configuration of adult and fetal brains in a population of Sri Lankan origin.
  
  
  METHODS
  The external diameter of the PcomA, pre-communicating part (P1), and the post-communicating part (P2) of posterior cerebral artery (PCA) of 34 fetal brain in the last trimester of pregnancy (30 to 40 weeks of gestation) was measured using a stereomicroscope equipped with a micrometer calibrator.
  
  
  RESULTS
  The blood supply to the occipital lobe mainly via the PCA was seen in 25 (59%) of fetal brains as compared to that in the literature 220 (93%) in adults brains and the blood supply to the occipital lobe mainly via the internal carotid artery (ICA) was seen in 16 (34%) of fetal brains as compared to 25 (7%) of adults brains (P < 0.0001), transitional configuration where the PcomA is equal in diameter to P1 segment of the PCA was seen in 5 (7.4%) of fetal brains and 8 (2%) of adults brains.
  
  
  CONCLUSIONS
  The present study reveals that from the newborn to the adult there is shift from carotid system to the vertebrobasilar system, this justifies further studies on different racial and geographic regions which may give a clearer picture about the cerebral hemodynamics from childhood to adult.
authors.affiliation: Department of Anatomy, Faculty of Medical Sciences, University of Sri Jayewardenepura, Nugegoda, Sri Lanka.
authors.forename: K Ranil D
authors.initials: KR
authors.lastname: De Silva
authors.forename: Rukmal
authors.initials: R
authors.lastname: Silva
authors.forename: Chandu
authors.initials: C
authors.lastname: De Silva
authors.forename: W S L
authors.initials: WS
authors.lastname: Gunasekera
authors.forename: P
authors.initials: P
authors.lastname: Dias
authors.forename: R W
authors.initials: RW
authors.lastname: Jayesekera