title: ISSLS Prize Winner: A Detailed Examination of the Elastic Network Leads to a New Understanding of Annulus Fibrosus Organization.
abstract: METHODS
  Investigation of the elastic network in disc annulus and its function.
  
  
  OBJECTIVE
  To investigate the involvement of the elastic network in the structural interconnectivity of the annulus and to examine its possible mechanical role.
  
  
  BACKGROUND
  The lamellae of the disc are now known to consist of bundles of collagen fibers organized into compartments. There is strong interconnectivity between adjacent compartments and between adjacent lamellae, possibly aided by a translamellar bridging network, containing blood vessels. An elastic network exists across the disc annulus and is particularly dense between the lamellae, and forms crossing bridges within the lamellae.
  
  
  METHODS
  Blocks of annulus taken from bovine caudal discs were studied in either their unloaded or radially stretched state then fixed and sectioned, and their structure analyzed optically using immunohistology.
  
  
  RESULTS
  An elastic network enclosed the collagen compartments, connecting the compartments with each other and with the elastic network of adjacent lamellae, formed an integrated network across the annulus, linking it together. Stretching experiments demonstrated the mechanical interconnectivities of the elastic fibers and the collagen compartments.
  
  
  CONCLUSIONS
  The annulus can be viewed as a modular structure organized into compartments of collagen bundles enclosed by an elastic sheath. The elastic network of these sheaths is interconnected mechanically across the entire annulus. This organization is also seen in the modular structure of tendon and muscle. The results provide a new understanding annulus structure and its interconnectivity, and contribute to fundamental structural information relevant to disc tissue engineering and mechanical modeling.
  
  
  METHODS
  N/A.
authors.affiliation: *Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK; and †Department of Chemical and Materials Engineering, University of Auckland, Auckland, New Zealand.
authors.forename: Jing
authors.initials: J
authors.lastname: Yu
authors.forename: Meredith L
authors.initials: ML
authors.lastname: Schollum
authors.forename: Kelly R
authors.initials: KR
authors.lastname: Wade
authors.forename: Neil D
authors.initials: ND
authors.lastname: Broom
authors.forename: Jill P G
authors.initials: JP
authors.lastname: Urban
mesh_terms: D000818:Animals; D002417:Cattle; D003094:Collagen / Q000502:physiology / Q000648:ultrastructure*; D004547:Elastic Tissue / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure*; D004549:Elastin / Q000032:analysis; D000071837:Fibrillins; D007403:Intervertebral Disc / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure*; D020894:Microfibrils / Q000737:chemistry / Q000000981:diagnostic imaging*; D008840:Microfilament Proteins / Q000032:analysis; D013314:Stress, Mechanical; D013718:Tensile Strength; D014463:Ultrasonography
chemical_list: D000071837:Fibrillins; D008840:Microfilament Proteins; D003094:Collagen; D004549:Elastin