Myelin sheath is derived from

Options

A. neuroglial cells
B. schwann cells
C. nerve cells
D. all of these

Answer

To answer the question "Myelin sheath is derived from," we will analyze the options provided and the information about myelin sheath.

### Step-by-Step Solution:

1. **Understanding Myelin Sheath**:
- Myelin sheath is an insulating layer that surrounds the axons of neurons. It is crucial for the proper functioning of the nervous system as it helps in the rapid transmission of electrical signals.

2. **Identifying the Source of Myelin**:
- Myelin is produced by specific types of cells. In the central nervous system (CNS), myelin is produced by oligodendrocytes. In the peripheral nervous system (PNS), myelin is produced by Schwann cells.

3. **Analyzing the Options**:
- The options given are:
- a) Neuroglial cell
- b) Schwann cell
- c) Nerve cell
- d) All of these
- Since Schwann cells are responsible for myelin production in the PNS, this option is valid.

4. **Conclusion**:
- The correct answer is **Schwann cell**, as it specifically refers to the cells that produce myelin in the peripheral nervous system. Although oligodendrocytes are also involved in myelin production, they are not listed as an option.

### Final Answer:
**Myelin sheath is derived from Schwann cells.**