How does zona pellucida of ovum help in preventing polyspermy?

Explanation

**Step-by-Step Text Solution:**

1. **Understanding Polyspermy**: Polyspermy refers to the phenomenon where more than one sperm enters an ovum during fertilization. This can lead to abnormal development of the embryo.

2. **Structure of the Ovum**: The ovum is surrounded by a protective layer known as the zona pellucida. This layer is composed of glycoproteins and serves as a barrier between the ovum and the surrounding environment.

3. **Role of Zona Pellucida**: The zona pellucida contains specific receptors, particularly ZP3 receptors, which are crucial for the fertilization process. When a sperm approaches the ovum, it binds to these ZP3 receptors.

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