Which part of sperm enters in egg in human ?

Options

A. Complete sperm
B. Only head
C. Head and middle piece
D. Head and acrosome

Answer

To answer the question "Which part of sperm enters in the egg in humans?", we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Sperm Structure**:
- The sperm consists of three main parts: the head, the middle piece, and the tail (or end piece). The head contains the nucleus and the acrosome, which is a cap-like structure filled with enzymes.

2. **Role of the Acrosome**:
- When a sperm approaches an egg, the acrosome releases enzymes that help digest the zona pellucida, which is the protective layer surrounding the egg.

3. **Entry of the Sperm**:
- The sperm must penetrate the zona pellucida to reach the egg. The head of the sperm is the part that first encounters the egg and is primarily responsible for this penetration.

4. **Correct Answer Identification**:
- Among the options given:
- Complete sperm: Incorrect, as the entire sperm does not enter the egg.
- Only head: Correct, as it is the head that enters the egg.
- Head and middle piece: Incorrect, as only the head enters.
- Head and acrosome: Incorrect, as the acrosome is part of the head.

5. **Conclusion**:
- The correct answer is that only the head of the sperm enters the egg in humans.

### Final Answer:
The part of the sperm that enters the egg in humans is **the only head**.

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