Days 8, 10, 12 and 15 (IMAGE) Duke University Caption The image shows the longitudinal UFF-PAM placenta on day 8, day 10, day 12, and day 15. Blood vessels diameter and density increased by more than 200% over this period. Credit Junjie Yao, Duke University Usage Restrictions Usage with credit 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.