Chorioid Plexus

Detail of histology of the chorioid plexus with blood vessels (cells in red color) within the stroma (stroma in blue color) which is lined by a cubic epithelium forming villi for increase of the surface. At this site a constant rate of 0.35 ml/min CSF is actively and passively formed and enters the ventricles. From the cranial lateral ventricles there is a constant flow in a caudal direction into the fourth ventricle; in addition, transependymal fluid is entering the ventricles.