Confocal Microscopy (IMAGE) Johns Hopkins Medicine Caption Confocal microscopy image of human embryonic kidney cells. Nanoparticles filled with human immunoglobulin were delivered to the cells. The cell nucleus is blue, endosomes (which sequester materials taken up by cells) are labeled in pink, and the immunoglobulin proteins are labeled with a green fluorescent tag. The nanoparticle's cargo has spread widely through most of the cells (green) without it being trapped in endosomes. Credit Yuan Rui, Johns Hopkins Medicine Usage Restrictions None 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.