Nodes of Ranvier are present in

Options

A. Non-myelinated neurons
B. Myelinated neurons
C. Non-medullated fibres
D. Both (1) and (2)

Answer

### Step-by-Step Solution:

1. **Understanding Neurons**: Neurons are the fundamental units of the nervous system. They can be classified into two types based on the presence of a myelin sheath: myelinated neurons and non-myelinated neurons.

2. **Defining Myelin Sheath**: The myelin sheath is a lipid-rich covering that insulates the axon of a neuron. It is crucial for the efficient transmission of electrical signals along the nerve fibers.

3. **Role of Schwann Cells**: The myelin sheath is produced by Schwann cells, which wrap around the axon. Each Schwann cell covers a segment of the axon, creating insulated areas.

4. **Identifying Nodes of Ranvier**: The Nodes of Ranvier are small gaps that occur between adjacent Schwann cells along the axon. These gaps are where the axon is not covered by the myelin sheath.

5. **Conclusion**: Since the Nodes of Ranvier are located at the junctions between segments of myelin sheath on the axon, they are found only in myelinated neurons. Therefore, the correct answer to the question is that Nodes of Ranvier are present in myelinated neurons.

### Final Answer:
**Nodes of Ranvier are present in myelinated neurons.**

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