Developing Mouse Heart (IMAGE) University of Pennsylvania School of Medicine Caption This is an image of remodeling valves in a 13.5-day-old embryonic mouse heart. Credit Lauren Goddard, PhD, 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.