The Signum or 'Vagina Dentata' (IMAGE) University of Cincinnati Caption This is a hinged, chewing jaw inside the female reproductive tract that helps her to mechanically break into the male spermatophore. Credit Nathan Morehouse Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.