Endosome (IMAGE) University of California - San Diego Caption A color electron micrograph of an endosome. Red visualizes the uptake of cell-penetrating peptides by green fluid-filled vesicles of the endosome (gray), a cell organelle involved in molecular transport. Credit Ranjan Ramachandra Usage Restrictions Use photo credit 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.