Fluorescently labeled sperm (IMAGE) University of Zurich Caption Using fluorescently labeled sperm, the researchers tracked the entire reproductive process. Credit Stefan Lüpold, UZH Usage Restrictions Credit must be given to the creator. License CC BY 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.