Oligodendrocytes differ from Schwann cells in that __________________.
 |
 |
oligodendrocytes occur in the peripheral nervous system, whereas Schwann cells occur in the central nervous system; |
 |
each oligodendrocyte forms multiple myelin sheaths, whereas each Schwann cell forms only one myelin sheath; |
 |
oligodendrocytes are composed primarily of fat, whereas Schwann cells are composed primarily of protein; |
 |
oligodendrocytes serve as axon insulators, whereas Schwann cells act as conductors of current flow; |
 |
none of the alternatives is correct; |