RAG1+ Green Immune Cells Crawl along Blood Vessels (video) Murdoch Childrens Research Institute Share Print E-Mail Loading video... Caption The bodies earliest immune cells were engineered to glow green when they arose from stem cells. These green cells can be seen migrating along blood vessels. Later, they populate the thymus - the so-called T-cell nursery. Credit Murdoch Children's Research Institute Usage Restrictions For use with this release only. Share Print E-Mail 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.