Answer: Oligodendrocytes (in CNS) or Schwann cells (in PNS).
- A Astrocytes, which regulate the blood-brain barrier
- B Schwann cells (in PNS) alone, with no CNS counterpart
- C Neurons themselves, by folding their own membrane
- D Oligodendrocytes (in CNS) or Schwann cells (in PNS)
Correct answer: D. Oligodendrocytes (in CNS) or Schwann cells (in PNS)
Explanation: Myelin sheath is formed by Schwann cells in the peripheral nervous system and by oligodendrocytes in the CNS. It speeds nerve impulses.
Structure of a neuron. Image: LadyofHats (Mariana Ruiz), Public Domain, via Wikimedia Commons.
Concept context
Brain, spinal cord, neurons, reflex arcs, and sense organs.