The Chiasmata is formed during which stage of Prophase-I of the Meiotic cell division?

Options

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

Answer

To determine during which stage of Prophase I the chiasmata is formed in meiotic cell division, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Stages of Prophase I**: Prophase I of meiosis consists of five sub-stages: leptotene, zygotene, pachytene, diplotene, and diakinesis. Each stage has distinct characteristics and events.

2. **Identify the Role of Chiasmata**: Chiasmata are points where homologous chromosomes exchange genetic material during meiosis. This process is crucial for genetic diversity.

3. **Analyze Each Stage**:
- **Leptotene**: Chromosomes begin to condense and become visible, but no pairing occurs.
- **Zygotene**: Homologous chromosomes start to pair up (synapsis), but chiasmata are not yet formed.
- **Pachytene**: This is where the homologous chromosomes are fully paired, and crossing over occurs. Chiasmata form during this stage as the chromatids exchange genetic material.
- **Diplotene**: The homologous chromosomes begin to separate but remain connected at the chiasmata.
- **Diakinesis**: The chromosomes condense further, and the chiasmata move towards the ends of the chromosomes.

4. **Conclusion**: The formation of chiasmata occurs during the **pachytene stage** of Prophase I.

### Final Answer:
The chiasmata is formed during the **pachytene stage** of Prophase I of meiotic cell division.