Meeting Abstract
Whales, dolphins, and porpoises have unusual vaginal folds of unknown function(s) that are hypothesized to play an important role in sexual selection. The functional morphology of vaginal folds was assessed by testing the mechanical properties of common bottlenose dolphin (Tursiops truncatus) reproductive tract tissues in 6 different regions and across age classes in post-mortem specimens. We assessed the regional and global effective elastic modulus of tissues using indentation and tensile tests. Age class, tissue type, type of force, and force values significantly affected the effective elastic modulus. The tissue was stiffest in the vaginal fold region and overall stiffer in sexually immature compared to mature animals. Reproductive tract tissue may increase in elastic modulus resulting from distension associated with copulation and parturition. Our data, combined with observations of mechanical interactions of genitalia during simulated copulation, suggest that the vaginal folds function as mechanical barriers to the penis and may provide females with mechanisms to control paternity.
