Final answer:
Ependymal cells are a type of glial cell responsible for producing and helping circulate cerebrospinal fluid in the CNS.
Step-by-step explanation:
Ependymal cells are a type of glial cell found in the central nervous system (CNS). These cells play a crucial role in producing cerebrospinal fluid (CSF), which circulates throughout the CNS. Ependymal cells line the ventricles in the brain and have cilia on their surface that help move CSF, thereby aiding in the circulation of this vital fluid. The choroid plexus is the specialized structure within the ventricles where ependymal cells come into contact with blood vessels and filter blood components to produce CSF. Thus, the correct answer to the question is that ependymal cells help to circulate the cerebrospinal fluid.