Microtubules appearing around centriole pair in the beginning of prophase in animal cells form

Options

A. Spindle
B. Aster
C. Spindle pole
D. Chromosome fibres

Answer

To solve the question regarding what microtubules appearing around the centriole pair in the beginning of prophase in animal cells form, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Prophase**:
- Prophase is the first stage of mitosis where the chromatin condenses into visible chromosomes, and the nuclear envelope begins to break down.

2. **Identifying the Role of Centrioles**:
- In animal cells, centrioles are crucial for organizing microtubules. They help in the formation of the spindle apparatus during cell division.

3. **Microtubule Formation**:
- During the beginning of prophase, microtubules begin to radiate from the centriole pairs. These microtubules are essential for the organization of the spindle apparatus.

4. **Options Analysis**:
- **Spindle**: While the spindle apparatus is formed during prophase, it is not fully established until later in prophase, making this option incorrect for the beginning of prophase.
- **Aster**: Asters are star-shaped structures that form around each centriole pair at the beginning of prophase. They consist of microtubules and play a role in organizing the spindle fibers.
- **Spindle Pole**: This term refers to the microtubule organizing center, which is specific to yeast cells, not animal cells. Therefore, this option is incorrect.
- **Chromosome Fibers**: These are not formed by microtubules; they refer to the genetic material and are not relevant to the question.

5. **Conclusion**:
- Based on the analysis, the correct answer is that the microtubules appearing around the centriole pair in the beginning of prophase in animal cells form **asters**.

### Final Answer:
Microtubules appearing around the centriole pair in the beginning of prophase in animal cells form **asters**.

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