A rat model to study the structural properties of the vagina and its supportive tissues

Objective The purpose of this study was to investigate the rat as a model for evaluating the structural properties of the vagina and its supportive tissues. Study design The in situ relationships between the vagina and its supportive tissues were studied grossly (n = 10), and in serial cross sections (n = 4). For biomechanical testing (n = 10), the lumbar spine was fixed to a testing machine while the distal vagina was gripped with a soft-tissue clamp mounted to a load-cell on the crosshead of the machine. The vagina was systematically pulled through the pelvis until failure of the supportive tissues occurred. Parameters describing the structural properties of the tissues (linear stiffness, ultimate load, ultimate elongation, and energy absorbed to failure) were determined from the resulting load-elongation curve. A coefficient of correlation (R) was used to determine experimental reproducibility. Results The rat vagina is supported by structures analogous to those in humans. The parameters describing the structural properties of these tissues were highly correlated among specimens (R = 0.95). The mechanism of failure was similar for all specimens. Conclusion We have developed a mechanical testing protocol in which the structural properties of the vagina-supportive tissue complex can be measured. This will be a powerful tool for testing the impact of life events on vaginal support.