Senescent Fibroblast Cells (IMAGE) Kumamoto University Caption Senescent fibroblast cells are metabolically active as shown by a large nucleolus (red) and increased mitochondria (green). Punctate DNA (blue) are the hallmark of senescent cells. Scale bar: 20 micrometers. Credit Professor Mitsuyoshi Nakao Usage Restrictions This image may only be used in conjunction with the accompanying release, or stories written about the work described in the release with reference to the original work. 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.