This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nerve, Subject name: Physiology
Myelin in CNS is formed by: 
Select and explain. 
A. Oligodendrocytes, B. Schwann cells, C. Microglia, D. Astrocytes
A: Oligodendrocytes
Answer: A: Oligodendrocytes 
Explanation: Myelin sheath in the CNS is formed by the oligodendrocytes; Myelin sheath of the peripheral nerves is formed by the Schwann cells.