Glossary · Definition · v2026.3
What Is the Zona Pellucida?
The zona pellucida is a glycoprotein shell that surrounds the egg and early embryo, protecting it and regulating interactions between sperm and egg during fertilization.
Clinical significance
In IVF laboratories the zona pellucida plays an important role in fertilization, embryo manipulation, and the hatching process that occurs before implantation. It is also involved in procedures such as assisted hatching.
Common confusion
Some people assume the zona pellucida remains permanently around the embryo. In reality, the embryo must hatch from this shell before implantation can occur.
Related reference
Used in
This content defines terminology for educational orientation. It does not constitute medical advice.
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