Zebrafish Hindbrain (IMAGE) University of Pennsylvania School of Medicine Caption This is a zebrafish hindbrain stained with an axonal marker in red and PAPPA-expressing neurons (green). Credit Michael Granato, PhD lab, Perelman School of Medicine, University of Pennsylvania 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.