title: The origin of the spinal subdural space: ultrastructure findings.
abstract: Previous studies of samples from cranial meninges have created doubts about the existence of a virtual subdural space. We examined the ultrastructure of spinal meninges from three human cadavers immediately after death to see whether there is a virtual subdural space at this level. The arachnoid mater had two portions: a compact laminar portion covering the dural sac internal surface and a trabecular portion extending like a spider web around the pia mater. There was a cellular interface between the laminar arachnoid and the internal layer of the dura that we called the dura-arachnoid interface. There was no subdural space in those specimens where the dura mater was macroscopically in continuity with the arachnoid trabecules. In the specimens where the dura mater was separated from the arachnoid, we found fissures in between the neurothelial cells that extended throughout the interface. We hypothesize that the subdural space would have its origin within the dura-arachnoid interface when the neurothelial cells break up, creating in this way a real subdural space.
  
  
  CONCLUSIONS
  The subdural space was not seen under transmission electron microscopy in samples of human spinal meninges where surgical manipulation was avoided. Scanning electron microscopy in other samples showed the presence of broken neurothelial cells giving up fissures that extended along the dura-arachnoid interface. These findings may explain the origin of a real subdural space.
authors.affiliation: Department of Anesthesiology and Critical Care, Hospital General de Móstoles, Hospital de Madrid Montepríncipe, Spain. miguelangel.rei@terra.es
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Reina
authors.forename: Oscar
authors.initials: O
authors.lastname: De Leon Casasola
authors.forename: Andrés
authors.initials: A
authors.lastname: López
authors.forename: José Antonio
authors.initials: JA
authors.lastname: De Andrés
authors.forename: Miguel
authors.initials: M
authors.lastname: Mora
authors.forename: Agustín
authors.initials: A
authors.lastname: Fernández
mesh_terms: D001099:Arachnoid / Q000648:ultrastructure; D004388:Dura Mater / Q000648:ultrastructure; D006801:Humans; D008161:Lumbosacral Region; D008578:Meninges / Q000648:ultrastructure*; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D013355:Subdural Space / Q000648:ultrastructure*