The choroid plexus (IMAGE) Boston Children's Hospital Caption Choroid plexus tissue (shown here in pink) is anchored in each of the brain's ventricles and bathed in cerebrospinal fluid. Though small, the choroid plexus is a key player in brain development and immunity. Credit Sebastian Stankiewicz, Boston Children's Hospital Usage Restrictions please credit as indicated 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.