In the given options, which one is a characteristic features of the zygotene stage to prophase - 1 observed in meiosis ?

Options

A. Chromomeres
B. Crossing over
C. Terminalisation of chiasmata
D. Synaptonemal complex

Answer

To solve the question regarding the characteristic features of the zygotene stage of prophase I in meiosis, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Meiosis**:
- Meiosis consists of two rounds of division (meiosis I and meiosis II) and includes several stages. Prophase I is the first stage of meiosis I and is subdivided into five stages: leptotene, zygotene, pachytene, diplotene, and diakinesis.

2. **Identifying the Zygotene Stage**:
- The zygotene stage is characterized by the pairing of homologous chromosomes. This process is known as synapsis, where homologous chromosomes align closely together.

3. **Formation of the Synaptonemal Complex**:
- During the zygotene stage, a structure called the synaptonemal complex forms. This complex is crucial for holding homologous chromosomes together and facilitating genetic recombination.

4. **Reviewing the Options**:
- The options provided include:
- Chromomeres
- Crossing over
- Terminalization of chiasmata
- Synaptonemal complex
- Among these, the formation of the synaptonemal complex is a defining feature of the zygotene stage.

5. **Conclusion**:
- Therefore, the correct answer to the question is **synaptonemal complex**, as it is specifically associated with the zygotene stage of prophase I in meiosis.