(IMAGE) Max-Planck-Gesellschaft Caption This image shows stem cells in the cortex of a mouse embryo (cell nuclei: blue). Credit MPI f. Molecular Cell Biology and Genetics/ D. Stenzel 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.