What are nodes of Ranvier ?Where are they present ?

Explanation

### Step-by-Step Solution:

1. **Definition of Nodes of Ranvier**:
- Nodes of Ranvier are small gaps or interruptions in the myelin sheath that surrounds the axon of a neuron. They are crucial for the proper functioning of nerve impulses.

2. **Structure of Myelinated Fibers**:
- The axon (or exome) of myelinated fibers is covered by a lipid-rich membrane known as the myelin sheath. This sheath is formed by specialized cells called Schwann cells.

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