Parts of an egg

Cuticle

Thin outermost coating inside the shell called the bloom or cuticle that helps keep out bacteria and dust.

Germinal disk

This is where the sperm enters the egg, it is a white line on the yolk.

Air cell

As the egg ages, moisture and carbon dioxide leave through the pores of the shell, air enters to replace them and the air cell becomes larger

Shell

Bumpy and grainy in texture, an eggshell is covered with as many as 17,000 tiny pores. Eggshell is made almost entirely of calcium carbonate (CaCO3) crystals. It is a semipermeable membrane, which means that air and moisture can pass through its pores.

Albumen

Four alternating layers of thick and thin albumen contain approximately 40 different proteins, the main components of the egg white in addition to water

Chalaza

Opaque ropes of egg white, the chalazae hold the yolk in the center of the egg. Like little anchors, they attach the yolk's casing to the membrane lining the eggshell

Vitelline membrane

The clear casing that encloses the yolk

Yolk

The yolk contains less water and more protein than the white, some fat, and most of the vitamins and minerals of the egg. These include iron, vitamin A, vitamin D, phosphorus, calcium, thiamine, and riboflavin. The yolk is also a source of lecithin, an effective emulsifier