Which of the following statements is correct for node of Ranvier of nerve?
- Neurilemma is discontinuous
- Myelin sheath is discontinuous
- Both neurilemma and myelin sheath are discontinuous
- Covered by myelin sheath
Answer
(2) Myelin sheath is discontinuous
Solution
As per NCERT, myelinated nerve fibres are enveloped with Schwann cells, which form a myelin sheath around the axon. The gaps between two adjacent myelin sheaths are called nodes of Ranvier.
⇒ At a node the myelin sheath is absent (discontinuous), while the neurilemma continues over it.
∴ At the node of Ranvier, the myelin sheath is discontinuous.
Answer: (2)