Without a Trace (IMAGE) European Molecular Biology Laboratory Caption A mass of migrating cells in the zebrafish embryo keep to one direction by vacuuming up the path behind them. Credit EMBL/E.Donà Usage Restrictions EMBL press and picture releases including photographs, graphics and videos are copyrighted by EMBL. They may be freely reprinted and distributed for non-commercial use via print, broadcast and electronic media, provided that proper attribution to authors, photographers and designers is made. 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.