# Choroid Plexus --- The **choroid plexus** is a complex tissue made up of [[epithelial tissue|epithelial cells]] and [[capillaries]] that line the [[brain ventricles|ventricles]] of the brain. It's main funciton is to produce the slick [[cerebrospinal fluid]] which cusions and protects the brain from friction, jostles, and being crushed under its own weight. ## Ependymal Cells **Ependymal cells** are the cells of the choroid plexus that are responsible for the production of [[cerebrospinal fluid|CSF]]. They are ciliated, and are either [[epithelial tissue#Simple Cuboidal|simple cuboidal]] or [[epithelial tissue#Simple Columnar|simple columnar]] cells. ## Blood-CSF Barrier The choroid plexus makes up one half of the **blood-CSF barrier**, which, like the [[blood-brain barrier]] prevents certain harmful substances from passing from the blood into the CSF, while still allowing good stuff to pass through and waste products to leave. The other half of the blood-CSF barrier is the [[meninges|arachnoid membrane]]. ___