Birth of blood-forming cells (IMAGE) Boston Children's Hospital Caption Clusters of the earliest hematopoietic cells being born in the walls of the umbilical artery of a mouse embryo. The cells colored in red represent embryonic multipotent progenitor cells (eMPPs). Credit Sachin H. Patel/Boston Children's Hospital Usage Restrictions Please credit as indicated. License Original 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.