title: Regional variation in tissue composition and biomechanical properties of postmenopausal ovine and human vagina.
abstract: OBJECTIVE
  There are increasing numbers of reports describing human vaginal tissue composition in women with and without pelvic organ prolapse with conflicting results. The aim of this study was to compare ovine and human posterior vaginal tissue in terms of histological and biochemical tissue composition and to assess passive biomechanical properties of ovine vagina to further characterise this animal model for pelvic organ prolapse research.
  
  
  METHODS
  Vaginal tissue was collected from ovariectomised sheep (n = 6) and from postmenopausal women (n = 7) from the proximal, middle and distal thirds. Tissue histology was analyzed using Masson's Trichrome staining; total collagen was quantified by hydroxyproline assays, collagen III/I+III ratios by delayed reduction SDS PAGE, glycosaminoglycans by dimethylmethylene blue assay, and elastic tissue associated proteins (ETAP) by amino acid analysis. Young's modulus, maximum stress/strain, and permanent strain following cyclic loading were determined in ovine vagina.
  
  
  RESULTS
  Both sheep and human vaginal tissue showed comparable tissue composition. Ovine vaginal tissue showed significantly higher total collagen and glycosaminoglycan values (p<0.05) nearest the cervix. No significant differences were found along the length of the human vagina for collagen, GAG or ETAP content. The proximal region was the stiffest (Young's modulus, p<0.05), strongest (maximum stress, p<0.05) compared to distal region, and most elastic (permanent strain).
  
  
  CONCLUSIONS
  Sheep tissue composition and mechanical properties showed regional differences along the postmenopausal vaginal wall not apparent in human vagina, although the absolute content of proteins were similar. Knowledge of this baseline variation in the composition and mechanical properties of the vaginal wall will assist future studies using sheep as a model for vaginal surgery.
authors.affiliation: The Ritchie Centre, MIMR-PHI Institute of Medical Research, Clayton, Victoria, Australia; Department of Obstetrics and Gynaecology, Monash Medical Centre, Monash University Melbourne, Victoria, Australia.
authors.forename: Daniela
authors.initials: D
authors.lastname: Ulrich
authors.affiliation: CSIRO Manufacturing Flagship, Clayton, Victoria, Australia.
authors.forename: Sharon L
authors.initials: SL
authors.lastname: Edwards
authors.affiliation: The Ritchie Centre, MIMR-PHI Institute of Medical Research, Clayton, Victoria, Australia; Department of Gynecology and Obstetrics, Caremeau University Hospital, Nimes, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Letouzey
authors.affiliation: CSIRO Manufacturing Flagship, Clayton, Victoria, Australia.
authors.forename: Kai
authors.initials: K
authors.lastname: Su
authors.affiliation: CSIRO Manufacturing Flagship, Clayton, Victoria, Australia.
authors.forename: Jacinta F
authors.initials: JF
authors.lastname: White
authors.affiliation: Department of Obstetrics and Gynaecology, Monash Medical Centre, Monash University Melbourne, Victoria, Australia.
authors.forename: Anna
authors.initials: A
authors.lastname: Rosamilia
authors.affiliation: The Ritchie Centre, MIMR-PHI Institute of Medical Research, Clayton, Victoria, Australia; Department of Obstetrics and Gynaecology, Monash Medical Centre, Monash University Melbourne, Victoria, Australia.
authors.forename: Caroline E
authors.initials: CE
authors.lastname: Gargett
authors.affiliation: CSIRO Manufacturing Flagship, Clayton, Victoria, Australia.
authors.forename: Jerome A
authors.initials: JA
authors.lastname: Werkmeister
mesh_terms: D000368:Aged; D000818:Animals; D001696:Biomechanical Phenomena; D003094:Collagen / Q000378:metabolism; D005260:Female; D006025:Glycosaminoglycans / Q000378:metabolism; D006801:Humans; D008875:Middle Aged; D056887:Pelvic Organ Prolapse; D017698:Postmenopause; D012756:Sheep; D014621:Vagina / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology*
chemical_list: D006025:Glycosaminoglycans; D003094:Collagen