Which stage is marked by terminalization of chiasmata?

Options

A. Zygotene
B. Pachytene
C. Diplotene
D. Diakinesis

Answer

To determine which stage is marked by terminalization of chiasmata, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Chiasmata**:
- Chiasmata are cross-shaped structures that form during meiosis when homologous chromosomes exchange genetic material. This occurs between non-sister chromatids of homologous chromosomes.

2. **Identifying the Stages of Meiosis**:
- Meiosis consists of two main stages: Meiosis I and Meiosis II. Meiosis I includes several phases: prophase I, metaphase I, anaphase I, and telophase I.

3. **Focusing on Prophase I**:
- Prophase I is further divided into five substages: leptotene, zygotene, pachytene, diplotene, and diakinesis.

4. **Understanding Each Substage**:
- **Leptotene**: Chromosomes begin to condense and become visible.
- **Zygotene**: Homologous chromosomes pair up (synapsis) and form a synaptonemal complex.
- **Pachytene**: Crossing over occurs, and chiasmata begin to form.
- **Diplotene**: The synaptonemal complex dissolves, and the chiasmata become visible.
- **Diakinesis**: This is the final stage of prophase I where the chromosomes condense further, and the chiasmata are terminalized, making them more visible.

5. **Conclusion**:
- The stage marked by terminalization of chiasmata is **diakinesis**.

### Final Answer:
The correct answer is **diakinesis**.

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