A chicken egg consists of several specialized parts, each with an important function in protecting and nourishing the developing embryo.
| Part | Function |
|---|---|
| Shell | Hard outer covering made mostly of calcium carbonate. Protects the egg while allowing gases to pass through tiny pores. |
| Shell Membranes | Two thin membranes (inner and outer) beneath the shell that help prevent bacteria from entering. |
| Air Cell | A pocket of air at the large end of the egg. It forms as the egg cools after being laid and grows larger as the egg ages. |
| Albumen (Egg White) | Provides water, protein, and protection against bacteria. It consists of thick and thin layers. |
| Chalazae | Twisted, rope-like strands of protein that anchor the yolk in the center of the egg. |
| Vitelline Membrane | Thin membrane surrounding the yolk, keeping it intact. |
| Yolk | Rich in fats, proteins, vitamins, and minerals. It is the primary nutrient source for the developing chick. |
| Germinal Disc (Blastodisc) | Small white spot on the yolk where embryo development begins if the egg is fertilized. |
Main Parts of a Chicken Egg
- Shell – Protective outer layer.
- Outer Shell Membrane – First protective membrane.
- Inner Shell Membrane – Second protective membrane.
- Air Cell – Air pocket at the broad end.
- Thin Albumen – Watery egg white.
- Thick Albumen – Dense egg white surrounding the yolk.
- Chalaza – Holds the yolk in place.
- Vitelline Membrane – Encloses the yolk.
- Yolk – Nutrient-rich center.
- Germinal Disc – Site of embryo formation in fertile eggs.
Interesting Facts
- A fresh egg has a small air cell, while an older egg has a larger air cell.
- The chalazae are a sign of freshness—they become less prominent as the egg ages.
- The shell contains approximately 7,000–17,000 microscopic pores, allowing oxygen and carbon dioxide to pass through.
- About 58–60% of an egg is albumen, 30–32% is yolk, and 9–11% is shell.
This anatomy is fundamental in poultry science, hatchery management, food science, and egg quality assessment.
