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Did you know?
Autoimmune diseases occur when the immune system destroys its own healthy tissues. When this occurs, white blood cells cannot distinguish between pathogens and normal cells.
Did you know?
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.
Did you know?
Elderly adults are living longer, and causes of death are shifting. At the same time, autopsy rates are at or near their lowest in history.
Did you know?
In the United States, there is a birth every 8 seconds, according to the U.S. Census Bureau's Population Clock.
Did you know?
The first-known contraceptive was crocodile dung, used in Egypt in 2000 BC. Condoms were also reportedly used, made of animal bladders or intestines.