|
|
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?
The human body produces and destroys 15 million blood cells every second.
Did you know?
Adult head lice are gray, about ? inch long, and often have a tiny dot on their backs. A female can lay between 50 and 150 eggs within the several weeks that she is alive. They feed on human blood.
Did you know?
Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.
Did you know?
The longest a person has survived after a heart transplant is 24 years.