Final answer:
True. Schmidt-Lanterman clefts are found in both the CNS and PNS.
Step-by-step explanation:
True. Schmidt-Lanterman clefts are found in both the Central Nervous System (CNS) and the Peripheral Nervous System (PNS).
Schmidt-Lanterman clefts are small invaginations or spaces within myelinated nerve fibers where the cytoplasm of Schwann cells is not completely compacted. They are more commonly found in the PNS, specifically in the myelin sheath of peripheral nerves. However, they can also occur in the CNS, particularly in the myelin sheath of oligodendrocytes in the brain and spinal cord.