An egg is an external womb that provides nourishment and protection for the growth and development of the embryo inside.

Creating an Egg
Eggs begin essentially as a food sac or yolk. The fertilized egg cell is part of the yolk and rests on its surface. It is the fertilized egg cell that grows into the embryo. As the yolk, or ovum, moves along the female bird’s reproductive tract, it is coated in albumen, or egg white, for protection. Then, shell membranes, the egg shell and the shell covering (cuticle), are added. The whole process takes about a day.

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