Question

multiple choice question
what is a myelin sheath composed of?
layers of glycoproteins
layers of carbohydrates
layers of proteins
layers of plasma membrane
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Explanation:

The myelin sheath is formed by Schwann cells (in the peripheral nervous system) or oligodendrocytes (in the central nervous system). These cells wrap around the axon multiple times. Each wrap consists of the plasma membrane of the glial cell. Glycoproteins, carbohydrates, and proteins are components of the plasma membrane but are not the main structural elements that make up the multiple - layered myelin sheath. The myelin sheath's structure is primarily due to the repeated layering of the plasma membrane of the glial cells.

Answer:

layers of plasma membrane