Endothelial Cells (IMAGE) Morgridge Institute for Research Caption These are healthy endothelial cells, which have an elongated shape and tend to grow in smooth, single-cell layers that comprise the inside surface of the artery. Credit Morgridge Institute for Research Usage Restrictions None License Licensed 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.