Final answer:
The statement is false as both blood and cerebrospinal fluid indirectly come into contact with neurons and glial cells in the CNS, with the blood-brain barrier regulating the exchange of substances.
Step-by-step explanation:
The statement is false. Both blood and cerebrospinal fluid (CSF) do come into contact with neurons and glial cells in the central nervous system (CNS), albeit indirectly. The blood-brain barrier (BBB) tightly regulates the exchange of substances between the blood and the brain interstitial fluid. However, some substances still pass through the BBB, such as glucose, amino acids, and certain gases. Furthermore, cerebrospinal fluid, which is produced from blood at the choroid plexuses, circulates through the CNS and does interact with the extracellular spaces of the brain and spinal cord.