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Egg cells are about the size of a grain of sand. They are formed inside of a female's ovaries before she is even born.
A cataract is a clouding of the eyes' natural lens. As we age, some clouding of the lens may occur. The first sign of a cataract is usually blurry vision. Although glasses and other visual aids may at first help a person with cataracts, surgery may become inevitable. Cataract surgery is very successful in restoring vision, and it is the most frequently performed surgery in the United States.
A seasonal flu vaccine is the best way to reduce the chances you will get seasonal influenza and spread it to others.
The familiar sounds of your heart are made by the heart's valves as they open and close.
Bacteria have flourished on the earth for over three billion years. They were the first life forms on the planet.

