Journal of anatomy
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Human spinal dura and arachnoid, obtained during neurosurgical operations, were studied by transmission electron microscopy. The ultrastructure of spinal meninges largely conformed to the morphology of the cranial meninges, but some minor differences were detected. The dura was composed of an outermost loosely arranged fibroelastic layer, a middle basically fibrous portion and an innermost cellular layer (dural border cell layer). ⋯ Morphological data suggest that the dura and arachnoid closely adhere at spinal levels in man without any naturally occurring "subdural space'. However, structurally, the dural border cell layer forms a weak cell layer at the dura-arachnoid continuum that is easily disrupted. The creation of an artifactual subdural space at spinal levels is discussed.