Why are such babies called test tube

Explanation

**Step-by-Step Solution:**

1. **Understanding the Concept of Test Tube Babies**: Test tube babies are a result of a process called In Vitro Fertilization (IVF), where fertilization occurs outside the human body.

2. **Fertilization Process**: In this process, the sperm from the father is combined with the egg from the mother in a controlled laboratory environment, typically in a petri dish or a test tube.

3. **Embryo Development**: After fertilization, the fertilized egg (now called an embryo) begins to develop. Some of this early development occurs in the laboratory setting, which is why it is referred to as a "test tube."

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