The assembly of spindle and disappearance of the nucleolus and nuclear envelope occurs in

Options

A. Metaphase - II
B. Telophase - I
C. Anaphase - II
D. Prophase - II

Answer

To solve the question regarding the phase of meiosis where the assembly of spindle fibers occurs along with the disappearance of the nucleolus and nuclear envelope, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Meiosis Phases**:
- Meiosis consists of two rounds of division: Meiosis I and Meiosis II. Each of these has distinct phases: prophase, metaphase, anaphase, and telophase.

2. **Identifying the Key Events**:
- The question specifically asks about the assembly of spindle fibers and the disappearance of the nucleolus and nuclear envelope. These events are crucial in the preparation for chromosome alignment and separation.

3. **Analyzing Each Option**:
- **Metaphase II**: In this phase, chromosomes align at the metaphase plate, but spindle assembly and nuclear envelope disappearance occur earlier.
- **Telophase I**: This phase is characterized by the reformation of the nuclear envelope and nucleolus, which makes it the opposite of what is described in the question.
- **Anaphase II**: During this phase, the chromosomes are pulled apart towards the poles, and the spindle fibers are already present from the previous phase.
- **Prophase II**: This is the phase where the chromosomes condense, and the spindle fibers assemble. The nucleolus and nuclear envelope disappear during this phase.

4. **Conclusion**:
- Based on the analysis, the correct answer is **Prophase II**. This is the phase where spindle fibers are assembled and the nucleolus and nuclear envelope disappear.

### Final Answer:
- The assembly of spindle and disappearance of the nucleolus and nuclear envelope occurs in **Prophase II** (Option 4).