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Sperm cells are so tiny that 400 to 500 million (400,000,000–500,000,000) of them fit onto 1 tsp.
Approximately 25% of all reported medication errors result from some kind of name confusion.
There are 20 feet of blood vessels in each square inch of human skin.
The first-known contraceptive was crocodile dung, used in Egypt in 2000 BC. Condoms were also reportedly used, made of animal bladders or intestines.
In most cases, kidneys can recover from almost complete loss of function, such as in acute kidney (renal) failure.
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