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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?
Normal urine is sterile. It contains fluids, salts, and waste products. It is free of bacteria, viruses, and fungi.
Did you know?
The immune system needs 9.5 hours of sleep in total darkness to recharge completely.
Did you know?
Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.
Did you know?
When blood is exposed to air, it clots. Heparin allows the blood to come in direct contact with air without clotting.