(IMAGE) National Institutes of Natural Sciences Caption Maturating sperm are centrally located and differentiation-competent stem cells, i.e. RARγpositive cells, are found in the periphery (brown). Credit National Institute for Basic Biology 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.