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Did you know?
Sperm cells are so tiny that 400 to 500 million (400,000,000–500,000,000) of them fit onto 1 tsp.
Did you know?
In 2012, nearly 24 milliion Americans, aged 12 and older, had abused an illicit drug, according to the National Institute on Drug Abuse (NIDA).
Did you know?
The familiar sounds of your heart are made by the heart's valves as they open and close.
Did you know?
There are more bacteria in your mouth than there are people in the world.
Did you know?
Intradermal injections are somewhat difficult to correctly administer because the skin layers are so thin that it is easy to accidentally punch through to the deeper subcutaneous layer.