Fluorescence image (IMAGE) University of Bonn Caption Fluorescence image of two zebrafish embryos - After switching off the Plexin-A1 gene (bottom), malformations of the nervous system occur, such as a pathological enlargement of the neural fluid spaces in the brain (left). Credit Dr. Gabriel Dworschak / University of Bonn Usage Restrictions Please use this image only in connection with the press release. 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.