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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.
Your skin wrinkles if you stay in the bathtub a long time because the outermost layer of skin (which consists of dead keratin) swells when it absorbs water. It is tightly attached to the skin below it, so it compensates for the increased area by wrinkling. This happens to the hands and feet because they have the thickest layer of dead keratin cells.
Pubic lice (crabs) are usually spread through sexual contact. You cannot catch them by using a public toilet.
Most fungi that pathogenically affect humans live in soil. If a person is not healthy, has an open wound, or is immunocompromised, a fungal infection can be very aggressive.
In the United States, congenital cytomegalovirus causes one child to become disabled almost every hour. CMV is the leading preventable viral cause of development disability in newborns. These disabilities include hearing or vision loss, and cerebral palsy.