Functional and Morphological Characteristics of Smooth Muscle in the Rat Vagina

The vagina is an essential organ of the female reproductive system that has been largely understudied in the field of biomechanics. The ability of the vagina to contract gives rise to a set of active mechanical properties that contribute to the complex function of this organ in-vivo. After briefly reviewing experimental studies on the active properties of the vagina, including the differences in contractility with respect to anatomic regions and orientations, neural pathways, life events, pelvic floor disorders, and surgical mesh treatment, we present our novel experimental studies that aim toward filling existing knowledge gaps on vaginal tissue morphology and contractile function of the vagina. First, we quantified the large heterogeneous deformations that the vagina experiences during contractions for the first time. For this study, vaginal specimens were subjected to isometric planar biaxial tests, during which they were induced to contract via KCl at four applied equi-biaxial stretches. The digital image correlation method was used to perform full-field strain analysis during each contraction. The vagina was found to have anisotropic contractile behavior, generating higher forces and experiencing higher magnitude strains along the longitudinal direction (LD) than along the circumferential direction (CD) during contractions. Then, we performed the first detailed quantification of the distribution and alignment of vaginal smooth muscle and nerves throughout the vagina. Toward this goal, vaginas from adult female rats were subjected to a tissue clearing and immunohistochemistry protocol. Tissue clearing increased the transparency of the specimens such that organs could be imaged without sectioning, thus preserving the 3D architecture of the tissue. This analysis revealed a bimodal distribution of muscle alignment angles, with a significantly higher proportion of muscle oriented along the LD than along the CD of the organ. The morphologic and functional properties of the smooth muscle within the healthy vagina need to be fully investigated so that detrimental alterations in vaginal contractility, such as those caused by pelvic floor disorders and current treatment strategies, can be prevented.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Engineering Mechanics

Department dc:contributor.department

Engineering Science and Mechanics

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2021

Author dc:creator

• Huntington, Alyssa Joan

Chair dc:contributor.committeechair

• De Vita, Raffaella

Committee members dc:contributor.committeemember

• Case, Scott W.
• Boreyko, Jonathan B.
• Wayne, Jennifer S.
• Wang, Vincent M.

• mechanics
• soft tissue
• reproductive
• smooth muscle

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

vt_gsexam:30113

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/112809