title: [Structural features of the smooth muscle cells in the medial layer of the bifurcation of fetal cerebral arteries].
abstract: OBJECTIVE
  To study the structural and histogenetic features of the smooth muscle cells (SMCs) in the medial layer of the bifurcation of human cerebral arteries in fetus.
  
  
  METHODS
  Segments of the cerebral arteries from the circle of Willis including the bifurcations of normal human fetuses were sectioned in 1 of the 3 orthogonal planes, wherein the three- dimensional medial layer structure composed of SMCs was observed with light microscope.
  
  
  RESULTS
  Microscopic observation identified 1.1 to 9.0 SMC layers in the medial layer of the cerebral arteries from the circle of Willis in the fetuses at different weeks before birth, and 30.3% of the specimens were found to have focal defects of the medial SMC layers at the bifurcation of the developing arteries.
  
  
  CONCLUSIONS
  The number of SMC layers consisted in the medial layers of the cerebral arteries develops with the fetal growth, and the identification of congenital anomaly of the medial SMCs may help verify the hypothetical pathogenesis for cerebral saccular aneurysms.
authors.affiliation: Department of Neurosurgery, Zhujiang Hospital, First Military Medical University, Guangzhou 510282, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Zhao
authors.forename: Tie-Lin
authors.initials: TL
authors.lastname: Li
authors.forename: Chuang-Zhi
authors.initials: CZ
authors.lastname: Duan
authors.forename: Jin
authors.initials: J
authors.lastname: Li
mesh_terms: D002536:Cerebral Arteries / Q000002:abnormalities* / Q000196:embryology; D005260:Female; D005333:Fetus; D006651:Histocytochemistry; D006801:Humans; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000002:abnormalities* / Q000196:embryology