title: The cerebral arterial circle (circulus arteriosus cerebri): an anatomical study in fetus and infant samples.
abstract: BACKGROUND
  Many studies have investigated the variations in the anatomy of each segment of the cerebral arterial circle while a few have addressed the variations of the cerebral arterial circle as a whole.
  
  
  METHODS
  Thirty brains of recently deceased Iranian infants and fetuses were dissected. The dissection process was filmed and digitized so as to be readily available for further studies. The variations of the circle as a whole and segmental variations were evaluated.
  
  
  RESULTS
  Variants with uni- and bilateral hypoplasia of posterior communicating arteries (PcoAs) were the most common in our study, similar to previous works. No aplasia of the precommunicating part of the anterior cerebral artery (A1), the precommunicating part of the posterior cerebral artery (P1) and anterior communicating artery was seen. Hypoplasia of the right and left PcoA was observed in 8 and 5 cases, respectively. Aplasia of the right PcoA was found in 16.6% and of the left PcoA in 3.3%.
  
  
  CONCLUSIONS
  In this study, we confirmed the previously described finding that the symmetrical, circular configuration of the circulus arteriosus cerebri is present in only about 42.1%. The main differences between the fetal and adult disposition are the diameter of the PcoA and the circular part of the posterior cerebral artery. According to previous studies, the fetal brain older than 4 months has anatomical characteristics very similar to the adult's circle; our finding was mostly similar to adult samples as most samples were from infants, not fetuses.
authors.affiliation: Department of Neurosurgery, Children's Hospital Medical Center, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Shahab Kamali
authors.initials: SK
authors.lastname: Ardakani
authors.forename: Majid
authors.initials: M
authors.lastname: Dadmehr
authors.forename: Farideh
authors.initials: F
authors.lastname: Nejat
authors.forename: Saeed
authors.initials: S
authors.lastname: Ansari
authors.forename: Behzad
authors.initials: B
authors.lastname: Eftekhar
authors.forename: Parvin
authors.initials: P
authors.lastname: Tajik
authors.forename: Mostafa
authors.initials: M
authors.lastname: El Khashab
authors.forename: Shahrooz
authors.initials: S
authors.lastname: Yazdani
authors.forename: Mohammad
authors.initials: M
authors.lastname: Ghodsi
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Mahjoub
authors.forename: Maryam
authors.initials: M
authors.lastname: Monajemzadeh
authors.forename: Bashir
authors.initials: B
authors.lastname: Nazparvar
authors.forename: Afshin
authors.initials: A
authors.lastname: Abdi-Rad
mesh_terms: D000367:Age Factors; D002941:Circle of Willis / Q000033:anatomy & histology* / Q000196:embryology* / Q000473:pathology; D005333:Fetus / Q000033:anatomy & histology* / Q000098:blood supply / Q000473:pathology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn