What Does Each Part of an Egg Do?

An egg's parts include the shell, the outer and inner membrane, the albumen, the chalazae, the yolk, and the germinal disc, and each of these parts help the chicken embryo develop. After a chicken lays the egg, an air cell forms at its large end when it cools to the environmental temperature.

The shell of an egg is a porous coating made of calcium carbonate that has as many as 7,000 tiny pores. Its job is to protect the embryo while still allowing the transfer of gases. Carbon dioxide and excess moisture leaves the egg, while atmospheric gases, such as oxygen, pass into the egg. The outer and inner membranes are beneath shell, and they protect the embryo from bacteria and help retain needed moisture.

The albumen, also known as the white of the egg, is the substance that the embryo grows in. It also provides protein for the embryo's development. Two chords, known as the chalazae, act as anchors for the egg yolk, holding it in place in the center of the egg.

The egg yolk is the part of the egg that provides nourishment for the chicken embryo. Within the yolk, there is a spot known as the germinal disc, which contains all the female's genetic information.