Germline Stem Cells (image) Salk Institute Caption An immunofluorescence image of the tip of the Drosophila testis, showing male germline stem cells and their daughters (green) responding to self renewal signals from the stem cell niche. Somatic stem cells, known as cyst progenitor cells, and differentiating cyst cells are labeled in red. Credit Dr. Monica Boyle Usage Restrictions News media reproduction to illustrate this story permitted with proper attribution as provided above. For one time use only 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.