title: Ultrastructural changes in the circumventricular organs after experimental subarachnoid hemorrhage.
abstract: OBJECTIVE
  Circumventricular organs (CVOs) are fine, periventricular, neurotransmitter-rich structures that are devoid of a blood-brain barrier and are known for their secretory role controlling fluid and electrolyte balance, thirst and even reproduction. Common pathologies of the brain such as trauma or bleeding affect CVOs, and hence their function. However, at what stage of these disease processes are CVOs affected and the time sequence of their recovery is still not clear. The aim of this study was to detect the morphological changes in CVOs using electron microscopy after experimental subarachnoid hemorrhage (SAH).
  
  
  METHODS
  Experimental SAH was induced by transclival puncture of the basilar artery. Both scanning and transmission electron microscopic examination of the representive sections from each CVO was undertaken.
  
  
  RESULTS
  Electron microscopy has shown that after SAH, the cells that form the CVOs exhibit signs of cellular necrosis with margination of the nucleus as well as cytoplasmic, mitochondrial and axonal edema. The subfornicial organ and organum vasculosum lamina terminalis appear to be more vulnerable to the effects of SAH than the median eminence or area postrema.
  
  
  CONCLUSIONS
  Considering the fact that the experimental SAH model we have used is very similar to the momentary rupture of an aneurysm with secondary reflex spasm to seal the hole, it will not be unrealistic to consider that similar effects may also take place in the clinical setting.
authors.affiliation: Bayindir Hospital, Department of Neurosurgery, Ankara, Turkey. gokhanakpinar@superonline.com
authors.forename: Gökhan
authors.initials: G
authors.lastname: Akpinar
authors.forename: Bektaş
authors.initials: B
authors.lastname: Açikgöz
authors.forename: Selçuk
authors.initials: S
authors.lastname: Sürücü
authors.forename: H Hamdi
authors.initials: HH
authors.lastname: Celik
authors.forename: Ferda
authors.initials: F
authors.lastname: Cağavi
mesh_terms: D000818:Animals; D002552:Cerebral Ventricles / Q000473:pathology* / Q000648:ultrastructure*; D004195:Disease Models, Animal; D008297:Male; D008854:Microscopy, Electron / Q000379:methods; D011677:Punctures / Q000379:methods; D051381:Rats; D013345:Subarachnoid Hemorrhage / Q000473:pathology*; D013356:Subfornical Organ / Q000473:pathology* / Q000648:ultrastructure*