Compounds Block Sperm's Power Kick (IMAGE) University of California - Berkeley Caption Compounds extracted from two plants, thunder god vine and aloe, prevent hyperactivation in sperm, the power kick necessary to fertilize the egg. The compounds are potential emergency contraceptives. Credit UC Berkeley illustration by Carin Cain: <a target="_blank"href="http://www.carincain.com/home/">http://www.carincain.com/home/</a> 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.