Fig. 1 (IMAGE) Osaka University Caption Sperm (red) reaching an egg in the female reproductive tract. Sperm lacking FER1L5 cannot undergo the acrosome reaction, and the acrosome (green) remains when it reaches the egg. Therefore, sperm are unable to fertilize eggs. Credit 2023, Masahito Ikawa, 2023 Morohoshi et al., Science Advances 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.