diagram (IMAGE) The Chinese University of Hong Kong Caption Under normal situation (image on the left), the closely packed choroid plexus restrains molecules in the blood stream from entering the CSF freely; the loss of SOX9 function (image on the right) resulted in the loss of collagen IX, eventually losing its protection against the entry of unwanted or harmful substance to the brain passing into the CSF. Credit CUHK 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.