title: Sheep lumbar intervertebral discs as models for human discs.
abstract: OBJECTIVE
  To determine the water content, collagen content and collagen orientation angle in different regions of sheep lumbar discs.
  
  
  METHODS
  A laboratory study of sheep discs obtained from an abattoir.
  
  
  METHODS
  A total of 21 sheep lumbar discs were obtained from three lumbar spines. Water content was determined by oven drying (60 degrees C) to constant mass. Collagen content was determined by hydroxyproline analysis. Fibre orientation angles were determined by X-ray diffraction.
  
  
  RESULTS
  Water content increased from 74% of total tissue mass in the outer annulus, to 82% in the inner annulus, to 86% in the nucleus. Collagen content decreased from 30% of total tissue mass in the outer region to 20% in the inner region of the anterior and lateral annulus; it was 16% in the posterior annulus. The orientation angle of the collagen fibres decreased from 59 degrees in the outer region to 56 degrees in the inner region of the anterior and lateral annulus; it was 51 degrees in the posterior annulus.
  
  
  CONCLUSIONS
  Sheep lumbar intervertebral discs provide a reasonable model for human lumbar intervertebral discs.
  
  
  CONCLUSIONS
  Sheep lumbar discs have been used to investigate the effects of removing and replacing the nucleus. These studies indicate that removal of nucleus may lead to further disc degeneration and indicate the material properties required for an implant material. The relevance of these previous studies is increased if human and sheep lumbar discs have a similar composition and structure.
authors.affiliation: Department of Bio-Medical Physics & Bio-Engineering, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK.
authors.forename: J E
authors.initials: JE
authors.lastname: Reid
authors.forename: J R
authors.initials: JR
authors.lastname: Meakin
authors.forename: S P
authors.initials: SP
authors.lastname: Robins
authors.forename: J M S
authors.initials: JM
authors.lastname: Skakle
authors.forename: D W L
authors.initials: DW
authors.lastname: Hukins
mesh_terms: D000818:Animals; D001834:Body Water / Q000378:metabolism; D003094:Collagen / Q000648:ultrastructure; D006801:Humans; D007403:Intervertebral Disc / Q000502:physiology* / Q000648:ultrastructure*; D008159:Lumbar Vertebrae; D023421:Models, Animal; D012680:Sensitivity and Specificity; D012756:Sheep; D013045:Species Specificity; D018709:Statistics, Nonparametric
chemical_list: D003094:Collagen