Each muscle is composed of many long, cylindrical fibres arranged in parallel arrays. These fibres are composed of numerous fine fibrils, called

Options

A. Microfilament
B. Myofibrils
C. Microtubule
D. Sarcoplasm

Answer

**Step-by-Step Solution:**

1. **Understanding Muscle Structure**: Each muscle is made up of long cylindrical fibers that are arranged in parallel arrays. These fibers are essential for muscle contraction and overall function.

2. **Identifying the Components of Muscle Fibers**: These muscle fibers are composed of smaller units called fibrils. It is important to identify what these fine fibrils are called.

3. **Analyzing the Options**: The question provides several options to choose from regarding what these fine fibrils are called. The options include:
- Microfilament
- Myofibrils
- Microtubule
- Sarcoplasm

4. **Evaluating Each Option**:
- **Microfilament**: This is a type of cytoskeleton made of actin, which is not the correct answer for muscle fibrils.
- **Myofibrils**: These are indeed the rod-like structures that make up muscle fibers. They are cylindrical and run parallel to each other, making this the correct answer.
- **Microtubule**: Another type of cytoskeleton, but not related to muscle fibrils.
- **Sarcoplasm**: This refers to the cytoplasm of muscle cells, not the fibrils themselves.

5. **Conclusion**: Based on the analysis, the fine fibrils that compose muscle fibers are called **myofibrils**.

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