Final answer:
Ependymal cells, a type of glial cell in the CNS, are most directly associated with the formation of CSF as they filter blood at the choroid plexus to produce this essential fluid.
Step-by-step explanation:
The cells most directly associated with the formation of cerebrospinal fluid (CSF) are the ependymal cells. Ependymal cells are a type of glial cell found in the central nervous system (CNS) that line the ventricular system. They are crucial in filtering blood to create CSF at the choroid plexus, a specialized structure within the ventricles. The CSF circulates through the CNS, providing buoyancy to the brain, removing waste, and acting as a shock absorber. Ependymal cells have an essential role in maintaining the blood-brain barrier (BBB) and ensuring the proper functioning of the CNS.