Germ Layers (image) Sanford-Burnham Medical Research Institute Caption These are differentiating mouse embryonic stem cells (green = mesoderm progenitor cells, red = endoderm progenitor cells). The microRNAs identified in this study block endoderm formation, while enhancing mesoderm formation. Credit Sanford-Burnham Medical Research Institute Usage Restrictions Free to use in conjunction with this story only, using provided credit and caption information 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.