Annals of Biomedical Engineering

, Volume 47, Issue 1, pp 272–281 | Cite as

Anisotropy of the Passive and Active Rat Vagina Under Biaxial Loading

  • Alyssa Huntington
  • Emanuele Rizzuto
  • Steven Abramowitch
  • Zaccaria Del Prete
  • Raffaella De VitaEmail author


Pelvic organ prolapse, the descent of the pelvic organs from their normal anatomical position, is a common condition among women that is associated with mechanical alterations of the vaginal wall. In order to characterize the complex mechanical behavior of the vagina, we performed planar biaxial tests of vaginal specimens in both the passive (relaxed) and active (contracted) states. Specimens were isolated from virgin, female Long-Evans rats (n = 16) and simultaneously stretched along the longitudinal direction (LD) and circumferential direction (CD) of the vagina. Tissue contraction was induced by electric field stimulation (EFS) at incrementally increasing values of stretch and, subsequently, by KCl. On average, the vagina was stiffer in the CD than in the LD (p < 0.001). The mean maximum EFS-induced active stress was significantly higher in the CD than in the LD (p < 0.01). On the contrary, the mean KCl-induced active stress was lower in the CD than in the LD (p < 0.01). When comparing the mean maximum EFS-induced active stress to the mean KCl-induced active stress, no differences were found in the CD (p = 0.366) but, in the LD, the mean active stress was much higher in response to the KCl stimulation (p < 0.001). Collectively, these results suggest that the anisotropic behavior of the vaginal tissue is determined not only by collagen and smooth muscle fiber organization but also by the innervation.


Vagina Biaxial tests Anisotropy Contractility Mechanical properties 



Funding was provided by NSF Grant No. 1511603.

Conflicts of interest

The authors have no conflict of interest.


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Copyright information

© Biomedical Engineering Society 2018

Authors and Affiliations

  • Alyssa Huntington
    • 1
  • Emanuele Rizzuto
    • 1
    • 2
  • Steven Abramowitch
    • 3
  • Zaccaria Del Prete
    • 2
  • Raffaella De Vita
    • 1
    Email author
  1. 1.STRETCH LaboratoryBlacksburgUSA
  2. 2.Department of Mechanical and Aerospace EngineeringLa Sapienza UniversityRomeItaly
  3. 3.Musculoskeletal Research CenterPittsburghUSA

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