Stem Cells in the Lab (IMAGE) Babraham Institute Caption These are stem cells from the brains of old an young mice grown into balls of cells called neurospheres. The slower growth of cells from older mice produces smaller spheres (lower image). Credit Dr. Giuseppe Lupo Usage Restrictions Please credit Dr. Giuseppe Lupo 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.