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The fine anatomy of the human spinal meninges. A light and scanning electron microscopy study
1Department of Neuropathology, Southampton University Medical School, England.
Abstract:
The fine anatomy of the human spinal meninges was examined in five postmortem spinal cords taken within 12 hours after death from patients aged 15 months to 46 years. Specimens of spinal cord were viewed in transverse section and from the dorsal and ventral aspects by scanning electron microscopy. Transverse sections of spinal cord and meninges were also examined by light microscopy. The arachnoid mater was seen to be closely applied to the inner aspect of the dura. An intermediate fenestrated leptomeningeal layer was observed attached to the inner aspect of the arachnoid mater and was reflected ventrally to form a series of dorsal septa. As it arborized laterally over the surface of the cord to surround nerves and blood vessels, the intermediate layer became highly fenestrated but remained distinct from the pia and arachnoid mater. The pia mater appeared to form a continuous layer which was reflected off the surface of the cord to coat blood vessels within the subarachnoid space in a manner similar to that described in the leptomeninges over the human cerebral cortex. Each dentate ligament consisted of a collagenous core which was continuous with the subpial connective tissue and was attached at intervals to the dura; pia-arachnoid cells coated the surface of the dentate ligaments. The present study suggests that the fine anatomy of the human spinal meninges differs significantly from that described in other mammals.
Insights
This study reveals a distinct intermediate leptomeningeal layer in human spinal meninges, differing from other mammals. This layer plays a key role in the spinal cord
Area of Science:
- Neuroscience
- Anatomy
- Histology
Background:
- The detailed structure of the human spinal meninges is not fully understood.
- Previous studies have primarily focused on non-human mammals, potentially overlooking human-specific features.
Purpose of the Study:
- To investigate the fine anatomical details of the human spinal meninges.
- To compare the human spinal meningeal structure with that of other mammalian species.
Main Methods:
- Examination of five postmortem human spinal cords using scanning electron microscopy (SEM) and light microscopy.
- Analysis of transverse sections and dorsal/ventral aspects of the spinal cord and meninges.
Main Results:
- Identification of a distinct, fenestrated intermediate leptomeningeal layer between the dura mater and pia mater.
- Observation that this layer forms dorsal septa and arborizes over the cord surface, surrounding nerves and blood vessels.
- The pia mater forms a continuous layer, investing blood vessels within the subarachnoid space, similar to cerebral leptomeninges.
Conclusions:
- The human spinal meninges possess a unique fine anatomical structure, including an intermediate leptomeningeal layer, that differs significantly from descriptions in other mammals.
- This finding necessitates a re-evaluation of existing models of spinal meningeal anatomy and function.