title: Age-related variation in cell density of human lumbar intervertebral disc.
abstract: METHODS
  changes in cell density of endplate (EP), nucleus pulposus (NP), and anulus fibrosus (AF) during ageing were systematically investigated in defined regions of interest in complete human motion segments.
  
  
  OBJECTIVE
  to elucidate cell density and total cell number in distinct anatomic regions of the intervertebral disc; to test effects of gender, level and age on cell density; and to correlate changes in cell density with histologic signs of disc degeneration.
  
  
  BACKGROUND
  the available information on the cell density within intervertebral discs and its age-related changes is sparse. This knowledge, however, is a crucial prerequisite for cell-based tissue engineering approaches of the intervertebral disc.
  
  
  METHODS
  in 49 complete cross-sections from lumbar motion segments (newborn to 86 years) from 22 specimens, cell density was determined by the Abercrombie method in EP, NP, and AF, and total cell number was counted per region of interest.
  
  
  RESULTS
  cell density in EP, NP, and AF decreased significantly from 0 to 16 years with the main changes occuring from 0 to 3 years for NP and AF. No significant variations were observed thereafter. We found a significant correlation of cell density and histologic degeneration score between 0 and 1, but not for scores >1. Gender and disc level did not influence cell density.
  
  
  CONCLUSIONS
  This study provides data concerning the total number of cells in the various regions of the intervertebral disc for different age groups. This knowledge will be beneficial for cell-based treatment approaches, which may evolve in the future.
authors.affiliation: Centre for Spinal Surgery, University of Zurich, University Hospital Balgrist, Forchstrasse, Zurich, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Liebscher
authors.forename: Mathias
authors.initials: M
authors.lastname: Haefeli
authors.forename: Karin
authors.initials: K
authors.lastname: Wuertz
authors.forename: Andreas G
authors.initials: AG
authors.lastname: Nerlich
authors.forename: Norbert
authors.initials: N
authors.lastname: Boos
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D000704:Analysis of Variance; D002452:Cell Count; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007403:Intervertebral Disc / Q000033:anatomy & histology / Q000166:cytology*; D055959:Intervertebral Disc Degeneration / Q000473:pathology*; D008159:Lumbar Vertebrae / Q000033:anatomy & histology / Q000166:cytology*; D008297:Male; D008875:Middle Aged; D055815:Young Adult