Mature Lamprey Gut (image) California Institute of Technology Share Print E-Mail Caption A side view of the lamprey gut, showing many large serotonergic neurons (green) sitting on the side of the gut. These gut neurons are matured and developed. Credit Courtesy of the Bronner laboratory Usage Restrictions WITH IMAGE CREDITS 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.