In which stage, you will find lampbrush chromosomes in oocyte of frog?

Options

A. In zygotene stage
B. Pachytene stage
C. In diplotene stage
D. Oocyte after fertilization

Answer

To find lampbrush chromosomes in the oocyte of a frog, we need to understand the stages of meiosis and the specific characteristics of lampbrush chromosomes. Here’s a step-by-step solution:

### Step-by-Step Solution:

1. **Understand Lampbrush Chromosomes**:
- Lampbrush chromosomes are a type of chromosome that is transcriptionally active and are found in the large oocytes of certain vertebrates, including frogs. They are characterized by their elongated structure and are involved in the active transcription of RNA.

2. **Identify the Stage of Meiosis**:
- Meiosis is a process that consists of two main divisions: meiosis I and meiosis II. Meiosis I is further divided into several stages: prophase I, metaphase I, anaphase I, and telophase I. Prophase I is also subdivided into five stages: leptotene, zygotene, pachytene, diplotene, and diakinesis.

3. **Locate the Formation of Lampbrush Chromosomes**:
- Lampbrush chromosomes specifically form during the diplotene stage of prophase I of meiosis. This occurs due to the active transcription of many genes, which leads to the uncoiling of the chromosomes.

4. **Eliminate Incorrect Options**:
- The question provides several options: zygote, pachytene, diplotene, and oocyte after fertilization.
- Zygote is the fertilized egg and does not have lampbrush chromosomes.
- Pachytene is the stage where crossing over occurs, but lampbrush chromosomes are not formed here.
- Oocyte after fertilization does not contain lampbrush chromosomes as they are specific to the diplotene stage.

5. **Conclusion**:
- Based on the information gathered, we conclude that lampbrush chromosomes in the oocyte of a frog are found during the diplotene stage of meiosis I.

### Final Answer:
Lampbrush chromosomes are found in the oocyte of a frog during the **diplotene stage** of meiosis I.

---