This image depicts a true wonder of nature. This tiny human sperm is penetrating a much larger egg. These two cells will unite to become a brand new human being. The process in which they unite is called fertilization. Do you know how sperm and egg cells are produced? When and where do they form? Do you know what will happen to the egg and sperm after they unite? How will the fertilized egg develop into a complete and very complex human being? You’ll find answers to all of these questions when you read this chapter.