This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nerve Physiology, Subject name: Physiology
[{'content': 'True about oligodendrocytes is? \nSelect and explain. \nA. Forms Myelin sheath, B. Forms blood brain barrier, C. Secretes CSF, D. All of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: ANSWER: (A) Forms Myelin sheathREF: Grays anatomy 39th ed page 51, Basic histology, Carlos & Jose, 11thedition, Chapter 9. Nerve Tissue & the Nervous System"The myelin sheath is produced by oligodendrocytes in the central nervous system and by Schwann cells in the peripheral nervous system"Oligodendrocytes myelinate CNS axons and are most commonly seen as intrafascicular cells in myelinated tracts.Oligodendrocytes may enclose up to 50 axons in separate myelin sheaths: the largest calibre axons are usually ensheathed on a 1:1 basis.', 'role': 'assistant'}]