The thread like structures that begin to radiate from each Centromene by the end of prophase are :

Options

A. aster microtubules
B. spindle microtubules
C. kinetochore microtubules
D. polar microtubules

Answer

To answer the question regarding the thread-like structures that begin to radiate from each centromere by the end of prophase, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Context of Prophase**:
- Prophase is the first stage of mitosis, where chromatin condenses into visible chromosomes, and the mitotic spindle begins to form.

2. **Identify the Structures Involved**:
- At the end of prophase, structures called centrioles are located at the poles of the cell. These centrioles are responsible for organizing the spindle fibers.

3. **Recognize the Role of Spindle Fibers**:
- The spindle fibers are essential for the separation of chromosomes during cell division. They originate from the centrioles.

4. **Focus on the Centromere and Kinetochore**:
- Each chromosome has a region called the centromere, which is crucial for the attachment of spindle fibers. The kinetochore is a protein complex that forms at the centromere and serves as the attachment point for the spindle fibers.

5. **Identify the Specific Type of Microtubules**:
- The thread-like structures radiating from each centromere are specifically known as **kinetochore microtubules**. These microtubules attach to the kinetochore and help in the movement of chromosomes toward the poles of the cell.

6. **Eliminate Incorrect Options**:
- Other types of microtubules mentioned (aster microtubules, spindle microtubules, and polar microtubules) serve different functions and are not specifically the ones radiating from the centromere during late prophase.

7. **Conclude the Answer**:
- Therefore, the correct answer to the question is **kinetochore microtubules**.

### Final Answer:
The thread-like structures that begin to radiate from each centromere by the end of prophase are **kinetochore microtubules**.

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