The parts of an egg include the shell, the inner and outer membranes, the air cell, the albumen, the chalazae, the vitelline membrane, the yolk and the germinal disc. The shell is hard and porous and serves as a protective layer that allows gases to be transferred in and out of the egg.
The outer and inner membranes are placed between the shell and the egg white and provide protection against bacterial invasion. The air cell is a space that forms after the egg is laid, when its contents lose heat and contract. The albumen is also known as the egg white.
The chalazae are cords made of mucin fibers that help the egg yolk maintain its central position. The vitelline membrane protects the yolk, which represents the food source for the embryo. The yolk also contains a small white spot that stores genetic material, called the germinal disc.