Retinoic Acid Gradients (IMAGE) RIKEN Caption These are retinoic acid gradients in a zebrafish embryo, visualized using cyan and yellow fluorophores. Credit RIKEN 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.