title: Levator ani muscle and connective tissue changes associated with pelvic organ prolapse, parity, and aging in the squirrel monkey: a histologic study.
abstract: OBJECTIVE
  This study was undertaken to evaluate histologically the levator ani muscle and paravaginal attachments in squirrel monkeys with and without pelvic organ prolapse.
  
  
  METHODS
  Serial sections from 19 females were processed with routine histology stains. Fiber typing was performed with antifast (type II) and antislow (type I) skeletal myosin antibodies, and apoptotic nuclei were examined by dUTP nick-end labeling (TUNEL).
  
  
  RESULTS
  Gross disruption of the levator ani muscle and its innervation was not observed in animals with or without visible support defects. Myogenic changes occurred more frequently in the pubocaudalis than iliocaudalis muscles, and a significant association was found with aging (P < .05, Fisher exact test) but not with pelvic organ prolapse or parity. Neurogenic changes were observed in 3 of 13 multiparous monkeys. Myocyte diameter increased in animals with pelvic organ prolapse compared with age-, weight-, and parity-matched animals without pelvic organ prolapse (P = .005) and correlated with levator ani muscle wet weight (R = 0.76; P = .0006). In the paravaginal attachments, the numbers of fibroblasts and apoptotic nuclei were not different between animals with and without pelvic organ prolapse, but parity was associated with increased apoptosis (P = .025).
  
  
  CONCLUSIONS
  Vaginal prolapse in the squirrel monkey does not result from atrophy or gross disruption of the levator ani muscle or its innervation. As in women, myogenic changes are a common finding in the levator ani muscle and increase with aging, whereas denervation with subsequent reinnervation occurs in some multiparous monkeys.
authors.affiliation: Department of Obstetrics and Gynecology, Scott & White Hospital, Temple, TX 76508, USA. lpierce@swmail.sw.org
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Pierce
authors.forename: Shannon
authors.initials: S
authors.lastname: Baumann
authors.forename: Michelle R
authors.initials: MR
authors.lastname: Rankin
authors.forename: Richard M
authors.initials: RM
authors.lastname: Wasserman
authors.forename: Arabella
authors.initials: A
authors.lastname: Biaggi
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Kuehl
authors.forename: Kimberly W
authors.initials: KW
authors.lastname: Coates
mesh_terms: D000375:Aging; D000818:Animals; D003238:Connective Tissue / Q000473:pathology* / Q000503:physiopathology; D005260:Female; D010298:Parity; D017773:Pelvic Floor / Q000473:pathology* / Q000503:physiopathology; D011247:Pregnancy; D012453:Saimiri; D014596:Uterine Prolapse / Q000503:physiopathology*