title: The presence and absence of lymphatic vessels in the adult human intervertebral disc: relation to disc pathology.
abstract: OBJECTIVE
  Although the normal adult human intervertebral disc is considered to be avascular, vascularised cellular fibrous tissue can be found in pathological conditions involving the disc such as disc herniation. Whether lymphatics vessels form a component of this reparative tissue is not known as the presence or absence of lymphatics in herniated and normal disc tissue is not known. We examined spinal tissues and discectomy specimens for the presence of lymphatics.
  
  
  METHODS
  The examination used immunohistochemistry to identify the specific lymphatic endothelial cell markers,podoplanin and LYVE1.
  
  
  RESULTS
  Lymphatic vessels were not found in the nucleus pulposus or annulus fibrosus of intact, non-herniated lumbar and thoracic discs but were present in the surrounding ligaments. Ingrowth of fibrous tissue was seen in 73% of herniated disc specimens of which 36% contained LYVE1+/podoplanin + lymphatic vessels. Lymphatic vessels were not seen in the sacrum and coccyx or biopsies of four sacrococcygeal chordomas, but they were noted in surrounding extra-osseous fat and fibrous tissue at the edge of the infiltrating tumour.
  
  
  CONCLUSIONS
  Our findings indicate that lymphatic vessels are not present in the normal adult intervertebral disc but that, when there is extrusion of disc material into surrounding soft tissue, there is ingrowth of reparative fibrous tissue containing lymphatic vessels. Our findings also indicate that chordoma, a tumour of notochordal origin, spreads to regional lymph nodes via lymphatics in para-spinal soft tissues.
authors.affiliation: Nuffield Department of Orthopaedic, Rheumatology and Musculoskeletal Science, University of Oxford, Oxford OX37LD, England.
authors.forename: Karolina
authors.initials: K
authors.lastname: Kliskey
authors.forename: Kelly
authors.initials: K
authors.lastname: Williams
authors.forename: J
authors.initials: J
authors.lastname: Yu
authors.forename: David
authors.initials: D
authors.lastname: Jackson
authors.forename: Jill
authors.initials: J
authors.lastname: Urban
authors.forename: Nick
authors.initials: N
authors.lastname: Athanasou
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007403:Intervertebral Disc / Q000473:pathology*; D007405:Intervertebral Disc Displacement / Q000473:pathology*; D008159:Lumbar Vertebrae / Q000473:pathology*; D042601:Lymphatic Vessels / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012447:Sacrum / Q000473:pathology*; D055815:Young Adult