Characteristics of smooth muscle fibres are

Options

A. Spindle -shaped , unbranched , unstriated , uninucleate and involuntary
B. Spindle -shaped , unbranched , unstriped , mutlinucleate and involuntary
C. Cylindrical , unbranced , unstriped , multinucleate and involuntary
D. Cylindrical , unbranched , striated , multinucleate and voluntary.

Answer

### Step-by-Step Solution:

1. **Definition of Smooth Muscle Fibers**:
- Smooth muscle fibers are a type of muscle tissue found in various organs, primarily in the digestive and urinary tracts.

2. **Location**:
- These fibers are mainly located in the digestive tract, which includes the small intestine, large intestine, and esophagus. They are also present in the urinary tract, which consists of the ureters and bladder.

3. **Cell Shape**:
- The cells of smooth muscle fibers are long and have pointed ends, which gives them a spindle shape. This characteristic is important for their function in contraction.

4. **Nucleus**:
- Smooth muscle fibers are uninucleated, meaning each cell contains a single nucleus. This is a distinguishing feature compared to other muscle types.

5. **Branching**:
- Smooth muscle fibers are unbranched, which means they do not form branches like cardiac muscle fibers do.

6. **Control**:
- These muscles are involuntary, meaning they are not under conscious control. They function automatically to regulate processes such as digestion and urination.

7. **Summary of Characteristics**:
- The main characteristics of smooth muscle fibers include:
- Spindle-shaped cells
- Uninucleated
- Unbranched
- Involuntary control
- Non-striated (unlike skeletal muscle)

### Final Answer:
The characteristics of smooth muscle fibers are:
- Spindle-shaped
- Uninucleated
- Unbranched
- Involuntary
- Non-striated

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