Watercolor of Endochondral Ossification (IMAGE) University of Pennsylvania School of Medicine Caption A watercolor image depicting the embryonic bone development process, endochondral ossification, featuring cartilage and bone. Credit Joel Boerckel Usage Restrictions Credit as specified. 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.