Synaptonemal complex is visible from

Options

A. Diplotene to Diakinesis
B. Leptotene to zygotene
C. zygotene to pachytene
D. Metaphase to Telophase

Answer

To determine when the synaptonemal complex is visible, we need to analyze the stages of meiosis, specifically focusing on prophase I.

### Step-by-Step Solution:

1. **Understanding Meiosis**: Meiosis is a type of cell division that reduces the chromosome number by half and is crucial for sexual reproduction. It consists of two main stages: meiosis I and meiosis II. The first stage, meiosis I, includes prophase I, which is further divided into several sub-stages.

2. **Identifying Prophase I Stages**: Prophase I is divided into five stages:
- **Leptotene**: Chromosomes begin to condense and become visible.
- **Zygotene**: Homologous chromosomes begin to pair up (synapsis), forming the synaptonemal complex.
- **Pachytene**: The paired chromosomes (bivalents) are fully formed, and crossing over occurs.
- **Diplotene**: The synaptonemal complex starts to dissolve, but the homologous chromosomes remain paired.
- **Diakinesis**: The chromosomes condense further, and the synaptonemal complex is no longer present.

3. **Determining Visibility of Synaptonemal Complex**: The synaptonemal complex is specifically visible during the zygotene stage when the homologous chromosomes are synapsed. It remains visible through the pachytene stage, where crossing over occurs. However, it begins to dissolve during the diplotene stage.

4. **Conclusion**: The synaptonemal complex is visible from the zygotene stage through to the pachytene stage, and it starts to disappear in the diplotene stage. Therefore, the correct answer to the question is that the synaptonemal complex is visible from **zygotene to pachytene**.

### Final Answer:
**The synaptonemal complex is visible from zygotene to pachytene.**