Growth in Muscle Layers Causes Wrinkling (image) Harvard University Share Print E-Mail Caption The wrinkling of the inner gut, Harvard researchers found, is intimately linked to the stages of muscle layer differentiation, which produce a series of different physical stresses. Credit Courtesy of L. Mahadevan and Science/AAAS. Usage Restrictions None Share Print E-Mail 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.