Growing Blood Vessels (IMAGE) British Heart Foundation Caption In green -- the endothelium. In orange -- stem cells adding to the blood vessel's lining. Credit BHF/Christiana Ruhrberg Usage Restrictions Credit must be included. 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.