A macrophage contacts a healthy stem cell (IMAGE) Boston Children's Hospital Caption A macrophage comes into close physical contact and appears to evaluate a stem cell that seems healthy, with little calreticulin on it surface. Credit Nymus 3D (https://nymus3d.nl/) Usage Restrictions Please credit as indicated. License Original 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.