Birth of Hematopoietic (Blood) Stem Cells (image) Cold Spring Harbor Laboratory Caption This shows early hematopoietic stem cells (blue) in a blood vessel of a mouse embryo. Credit Nancy Speck, University of Pennsylvania School of Medicine Usage Restrictions Image may only be used with appropriate credit to the source. 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.