Cells (image) Helmholtz Association Caption Stem cells are not specialised, propagate without limit and can develop to different cell types. From these the different cell and tissue types of the human organism, including the allergy-promoting eosinophil granulocytes, are differentiated. Progenitor cells, e.g. eosinophil/basophilic progenitors shown in the picture, which mature in the bone marrow and are then washed out into the bloodstream -- the so-called periphery -- function as a link between unspecialised stem cells and specialised tissue and organ cells. Credit Photo: Dr. Kristin Weiße/UFZ CC BY 3.0 (http://creativecommons.org/licenses/by/3.0/) Usage Restrictions None 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.