Anatomical and histological characterization of the filum terminale in dogs
The filum terminale (FT) remains poorly characterized in the veterinary literature, limiting understanding of its role in spinal cord and nerve root pathologies such as tethered cord syndrome. This study aimed to establish baseline anatomical and histological features of the FT in neurologically nor...
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Frontiers Media S.A.
2025-07-01
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| Series: | Frontiers in Veterinary Science |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fvets.2025.1650893/full |
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| author | Christoforos Posporis Javier Espinosa Martí Pumarola Ester Blasco Ortega Jaume Alomar Koen Santifort Koen Santifort Steven De Decker Karol Lam Juan José Mínguez Patricia Álvarez Vicente Aige-Gil |
| author_facet | Christoforos Posporis Javier Espinosa Martí Pumarola Ester Blasco Ortega Jaume Alomar Koen Santifort Koen Santifort Steven De Decker Karol Lam Juan José Mínguez Patricia Álvarez Vicente Aige-Gil |
| author_sort | Christoforos Posporis |
| collection | DOAJ |
| description | The filum terminale (FT) remains poorly characterized in the veterinary literature, limiting understanding of its role in spinal cord and nerve root pathologies such as tethered cord syndrome. This study aimed to establish baseline anatomical and histological features of the FT in neurologically normal dogs. Eight adult canine cadavers euthanized for non-neurological reasons were examined. Dissection was performed via dorsal laminectomy (n = 4) and midline sectioning (n = 4). Histological analysis (n = 4) included hematoxylin and eosin, Klüver-Barrera, Masson’s trichrome, and Verhoeff-Van Gieson stains, alongside immunohistochemistry for neuron-specific enolase, protein gene product 9.5, and glial fibrillary acidic protein. Grossly, the FT was identified as a direct continuation of the conus medullaris within the region of the vertebral canal at L6, extending caudally to form two segments: a cranial portion within the subarachnoid space of the dural sac (filum terminale internum, FTi) and a caudal portion beyond the dural sac, enclosed by the inner dural layer without intervening subarachnoid space (filum terminale externum, FTe). The dural sac terminated at the level of mid-sacrum, with the FTe extending further caudally to insert dorsally between the first and second caudal vertebrae. The FT was accompanied by a ventral artery and vein. Histologically, the FT retained vestigial spinal cord cytoarchitecture, including an irregular, folded central canal with ependymal lining, a subependymal astrocytic layer, gray matter with scattered neurons and glial cells, and peripheral white matter with myelinated axons. The central canal and the neuronal and glial elements progressively diminished caudally as the FT transitioned to collagenous tissue interspersed with sparse residual nerve fibers. Verhoeff-Van Gieson staining revealed minimal elastic fibers within the collagen matrix. This study presents the first comprehensive anatomical and histological characterization of the normal canine FT, establishing baseline reference data to facilitate the identification of pathomorphological alterations associated with disorders involving this structure, such as tethered cord syndrome. |
| format | Article |
| id | doaj-art-e429473591f3450abbc1315e1de8793c |
| institution | DOAJ |
| issn | 2297-1769 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | Frontiers Media S.A. |
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| series | Frontiers in Veterinary Science |
| spelling | doaj-art-e429473591f3450abbc1315e1de8793c2025-08-20T03:15:26ZengFrontiers Media S.A.Frontiers in Veterinary Science2297-17692025-07-011210.3389/fvets.2025.16508931650893Anatomical and histological characterization of the filum terminale in dogsChristoforos Posporis0Javier Espinosa1Martí Pumarola2Ester Blasco Ortega3Jaume Alomar4Koen Santifort5Koen Santifort6Steven De Decker7Karol Lam8Juan José Mínguez9Patricia Álvarez10Vicente Aige-Gil11Neurology and Neurosurgery Department, Independent Vetcare (IVC) Evidensia, Pride Veterinary Referrals, Derby, United KingdomNeurology and Neurosurgery Department, Independent Vetcare (IVC) Evidensia, Pride Veterinary Referrals, Derby, United KingdomMouse and Comparative Pathology Unit, Department of Animal Medicine and Surgery, Veterinary Faculty, Universitat Autònoma de Barcelona, Barcelona, SpainMouse and Comparative Pathology Unit, Department of Animal Medicine and Surgery, Veterinary Faculty, Universitat Autònoma de Barcelona, Barcelona, SpainMouse and Comparative Pathology Unit, Department of Animal Medicine and Surgery, Veterinary Faculty, Universitat Autònoma de Barcelona, Barcelona, SpainNeurology and Neurosurgery Department, Independent Vetcare (IVC) Evidensia, Dierenziekenhuis Arnhem, Arnhem, NetherlandsNeurology and Neurosurgery Department, Independent Vetcare (IVC) Evidensia, Dierenziekenhuis Hart van Brabant, Waalwijk, NetherlandsDepartment of Clinical Science and Services, Royal Veterinary College, Hatfield, United KingdomNeurology and Neurosurgery Department, Independent Vetcare (IVC) Evidensia, Pride Veterinary Referrals, Derby, United KingdomNeurology and Neurosurgery Department, Independent Vetcare (IVC) Evidensia, Pride Veterinary Referrals, Derby, United KingdomNeurology and Neurosurgery Department, Independent Vetcare (IVC) Evidensia, Pride Veterinary Referrals, Derby, United KingdomDepartment of Animal Health and Anatomy, Veterinary Faculty, Universitat Autònoma de Barcelona, Barcelona, SpainThe filum terminale (FT) remains poorly characterized in the veterinary literature, limiting understanding of its role in spinal cord and nerve root pathologies such as tethered cord syndrome. This study aimed to establish baseline anatomical and histological features of the FT in neurologically normal dogs. Eight adult canine cadavers euthanized for non-neurological reasons were examined. Dissection was performed via dorsal laminectomy (n = 4) and midline sectioning (n = 4). Histological analysis (n = 4) included hematoxylin and eosin, Klüver-Barrera, Masson’s trichrome, and Verhoeff-Van Gieson stains, alongside immunohistochemistry for neuron-specific enolase, protein gene product 9.5, and glial fibrillary acidic protein. Grossly, the FT was identified as a direct continuation of the conus medullaris within the region of the vertebral canal at L6, extending caudally to form two segments: a cranial portion within the subarachnoid space of the dural sac (filum terminale internum, FTi) and a caudal portion beyond the dural sac, enclosed by the inner dural layer without intervening subarachnoid space (filum terminale externum, FTe). The dural sac terminated at the level of mid-sacrum, with the FTe extending further caudally to insert dorsally between the first and second caudal vertebrae. The FT was accompanied by a ventral artery and vein. Histologically, the FT retained vestigial spinal cord cytoarchitecture, including an irregular, folded central canal with ependymal lining, a subependymal astrocytic layer, gray matter with scattered neurons and glial cells, and peripheral white matter with myelinated axons. The central canal and the neuronal and glial elements progressively diminished caudally as the FT transitioned to collagenous tissue interspersed with sparse residual nerve fibers. Verhoeff-Van Gieson staining revealed minimal elastic fibers within the collagen matrix. This study presents the first comprehensive anatomical and histological characterization of the normal canine FT, establishing baseline reference data to facilitate the identification of pathomorphological alterations associated with disorders involving this structure, such as tethered cord syndrome.https://www.frontiersin.org/articles/10.3389/fvets.2025.1650893/fulldural sacconus medullarisependymaneuronsgliacollagen |
| spellingShingle | Christoforos Posporis Javier Espinosa Martí Pumarola Ester Blasco Ortega Jaume Alomar Koen Santifort Koen Santifort Steven De Decker Karol Lam Juan José Mínguez Patricia Álvarez Vicente Aige-Gil Anatomical and histological characterization of the filum terminale in dogs Frontiers in Veterinary Science dural sac conus medullaris ependyma neurons glia collagen |
| title | Anatomical and histological characterization of the filum terminale in dogs |
| title_full | Anatomical and histological characterization of the filum terminale in dogs |
| title_fullStr | Anatomical and histological characterization of the filum terminale in dogs |
| title_full_unstemmed | Anatomical and histological characterization of the filum terminale in dogs |
| title_short | Anatomical and histological characterization of the filum terminale in dogs |
| title_sort | anatomical and histological characterization of the filum terminale in dogs |
| topic | dural sac conus medullaris ependyma neurons glia collagen |
| url | https://www.frontiersin.org/articles/10.3389/fvets.2025.1650893/full |
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