Fertilization is a complex process. Fertilization occurs when the secondary oocyte and spermatozoon meet in the fallopian tube of the female body. The stages of fertilization are:
1. Hyaluronidase enzyme is secreted from sperm acrosome. This enzyme creates a pathway for sperm to travel to the egg.
2. The spermatozoon travels to the zona pellucida of the egg. Later, the sperm collector and egg collector form a bond.
3. When the bond is formed, the sperm is stimulated and an enzyme is released from the sperm head. This enzyme breaks down the zona pellucida of the ovum to create an entrance. Through the entrance, the sperm head enters the egg.
4. Lysozyme enzyme is released from the egg as soon as the sperm head enters the egg. This enzyme hardens and thickens the zona pellucida. As a result, no more sperm can penetrate through the zona pellucida.
5. After sperm penetration, the secondary oocyte divides to form the ovum and polar body. Polar bodies are destroyed. The sperm and egg nuclei are swollen. It is called pronucleus.
6. Pronuclei of sperm and egg fuse to form zygote.