Multiple choice In central nervous system white matter accomodates numerous nerve cell bodies the myelin fibres are created by Schwann cells neurons are conserved from changes in plasma composition the cerebrospinal fluid is an ultrafiltrate of blood plasma Reveal answer Fill a bubble to check yourself C Correct answer Explanation In the central nervous system, the neurons are conserved from changes in plasma composition. The blood-brain barrier isolates central neurons from alterations to plasma composition.