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

Options

A. Embryo only, upto 8 cell stage
B. either zygote or early embryo upto 8 cell stage
C. embryo of 32 cell stage
D. zygote only

Answer

### Step-by-Step Solution:

1. **Understanding In Vitro Fertilization (IVF)**:
- In vitro fertilization is a reproductive technology where fertilization occurs outside the body, typically in a laboratory setting (often referred to as a "test tube").

2. **Formation of Zygote**:
- During IVF, sperm and egg are combined to form a zygote. This zygote is the initial cell formed when a sperm fertilizes an egg.

3. **Development of Embryo**:
- After the zygote is formed, it undergoes several divisions and develops into an embryo. The embryo can be at different stages of development, such as the 2-cell stage, 4-cell stage, 8-cell stage, and so on.

4. **Transfer to Fallopian Tube**:
- In the context of IVF, the zygote or an early-stage embryo (up to the 8-cell stage) can be transferred into the fallopian tube. This is done to allow for further development before implantation.

5. **Correct Answer**:
- The question asks for what is transferred into the fallopian tube during IVF. The correct answer is that either the zygote or an embryo up to the 8-cell stage is transferred into the fallopian tube.

### Final Answer:
In vitro fertilization involves the transfer of a zygote or an embryo up to the 8-cell stage into the fallopian tube.

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