Name chief layers of human ovum.

Explanation

**Step-by-Step Solution:**

1. **Identify the Ovum Structure**: The human ovum, or egg, is a female gamete that consists of several layers surrounding its cytoplasm.

2. **First Layer - Plasma Membrane (White Line Membrane)**: The outermost layer of the ovum is known as the plasma membrane, which is also referred to as the white line membrane. This membrane serves as a protective barrier for the ovum.

3. **Formation of Fertilization Membrane**: Upon fertilization by a sperm, the plasma membrane transforms into a fertilization membrane. This change prevents other sperm from penetrating the ovum, thus protecting it from polyspermy (the entry of multiple sperm).

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