title: Architectural assessment of rhesus macaque pelvic floor muscles: comparison for use as a human model.
abstract: OBJECTIVE
  Animal models are essential to further our understanding of the independent and combined function of human pelvic floor muscles (PFMs), as direct studies in women are limited. To assure suitability of the rhesus macaque (RM), we compared RM and human PFM architecture, the strongest predictor of muscle function. We hypothesized that relative to other models, RM best resembles human PFM.
  
  
  METHODS
  Major architectural parameters of cadaveric human coccygeus, iliococcygeus, and pubovisceralis (pubococcygeus + puborectalis) and corresponding RM coccygeus, iliocaudalis, and pubovisceralis (pubovaginalis + pubocaudalis) were compared using 1- and 2-way analysis of variance (ANOVA) with post hoc testing. Architectural difference index (ADI), a combined measure of functionally relevant structural parameters predictive of length-tension, force-generation, and excursional muscle properties was used to compare PFMs across RM, rabbit, rat, and mouse.
  
  
  RESULTS
  RM and human PFMs were similar with respect to architecture. However, the magnitude of similarity varied between individual muscles, with the architecture of the most distinct RM PFM, iliocaudalis, being well suited for quadrupedal locomotion. Except for the pubovaginalis, RM PFMs inserted onto caudal vertebrae, analogous to all tailed animals. Comparison of the PFM complex architecture across species revealed the lowest, thus closest to human, ADI for RM (1.9), followed by rat (2.0), mouse (2.6), and rabbit (4.7).
  
  
  CONCLUSIONS
  Overall, RM provides the closest architectural representation of human PFM complex among species examined; however, differences between individual PFMs should be taken into consideration. As RM is closely followed by rat with respect to PFM similarity with humans, this less-sentient and substantially cheaper model is a good alternative for PFM studies.
authors.affiliation: Reproductive Medicine, University of California, La Jolla, San Diego, CA, USA.
authors.forename: Amanda M
authors.initials: AM
authors.lastname: Stewart
authors.affiliation: Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Cook
authors.affiliation: Orthopaedic Surgery, University of California, La Jolla, San Diego, CA, USA.
authors.forename: Mary C
authors.initials: MC
authors.lastname: Esparza
authors.affiliation: Division of Reproductive & Developmental Sciences, Oregon National Primate Research Center, Beaverton, OR, USA.
authors.forename: Ov D
authors.initials: OD
authors.lastname: Slayden
authors.affiliation: Reproductive Medicine, Division of Urogynecology and Reconstructive Pelvic Surgery, University of California, 9500 Gilman Drive, La Jolla, San Diego, CA, 92093-0863, USA. malperin@ucsd.edu.
authors.forename: Marianna
authors.identifier: http://orcid.org/0000-0002-6004-1803
authors.initials: M
authors.lastname: Alperin
mesh_terms: D000328:Adult; D000818:Animals; D003094:Collagen / Q000032:analysis; D005260:Female; D006801:Humans; D008253:Macaca mulatta / Q000033:anatomy & histology*; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000737:chemistry; D017773:Pelvic Floor / Q000033:anatomy & histology*
chemical_list: D003094:Collagen
keywords: Muscle architecture; Pelvic floor muscles; Rhesus macaque