The correct term to fill in the blank is ependymal cells. Ependymal cells are a type of glial cell found in the central nervous system (CNS). They line the ventricles of the brain and the central canal of the spinal cord, where they play a crucial role in the production and circulation of cerebrospinal fluid (CSF).
These cells have cilia on their surface that help in the movement of the CSF, ensuring that it flows properly throughout the brain and spinal cord. This circulation is essential for maintaining the brain’s environment, providing cushioning, and removing waste products. Thus, ependymal cells are vital for the overall health and function of the CNS.