Stem Cell Plasticity (IMAGE) University of Pennsylvania Caption A stem cell nucleus flows like a soft plastic. The chromatin fibers are tagged yellow and a dark stripe is painted to help visualize the flow into a micro-capillary. Credit Proceedings of the National Academy of Sciences and the University of Pennsylvania Usage Restrictions For permissions, contact the Proceedings of the National Academy of Sciences. 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.