In vitro fertilization is a technique that involves transfer of which one of the following into the fallopian tube?

Options

A. Either zygote or early embryi up to 8 cell stage
B. Embryo only, up to 8 cell stage
C. Embryo of 32 cell stage
D. Zygote only

Answer

**Step-by-Step Solution:**

1. **Understanding In Vitro Fertilization (IVF)**: IVF is a reproductive technology where fertilization occurs outside the body. The process involves several steps, including superovulation, egg retrieval, fertilization, and embryo transfer.

2. **Superovulation**: In IVF, superovulation is induced to release multiple eggs. This is often achieved using hormones like clomiphene or gonadotropins.

3. **Egg Retrieval**: Once the eggs are matured, they are retrieved from the ovaries. This is done through a minor surgical procedure.

4. **Fertilization**: The retrieved eggs are then fertilized with sperm. This can be done through traditional insemination or a method called ICSI (Intracytoplasmic Sperm Injection), where a single sperm is injected directly into an egg.

5. **Embryo Development**: After fertilization, the zygote begins to divide. The early stages of division lead to the formation of an embryo. The embryo can be at various stages, commonly at the 2-cell stage or the 8-cell stage.

6. **Embryo Transfer**: The key step in IVF is transferring the developed embryo into the fallopian tube. This can be done with either a zygote (fertilized egg) or an early embryo (up to the 8-cell stage).

7. **Identifying the Correct Answer**: The question asks which entity is transferred into the fallopian tube during IVF. Based on the process, the correct answer is either a zygote or an early embryo (up to the 8-cell stage).

8. **Final Answer**: The correct option is **A**: either zygote or early embryo up to the 8-cell stage.

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