Women of child-bearing age steadily run out of eggs by the continuous process of cell death. While reading a copy of the 'Guardian' carefully from cover to cover, a normal woman will have lost on average two eggs - while, typically, a normal man will have made 70,000 new sperm.
The egg of every species of animal or plant carries a definite number of bodies called chromosomes. The sperm carries the same number. Consequently, when the sperm unites with the egg, the fertilized egg will contain the double number of chromosomes.
Every batch of sperm represents an opportunity for genetic typos - called de novo mutations - to be passed on. A 20-year-old man and woman will each pass on about 20 de novo mutations to a baby they conceive. By the time the couple is 40, a woman's total has remained at 20, while a man's has jumped to 65 - and it keeps climbing from there.
Football is a fertility festival. Eleven sperm trying to get into the egg. I feel sorry for the goalkeeper.
When sperm and egg unite, something goes from inanimate to animate. It is life.
It is a well-documented fact that guys will not ask for directions. This is a biological thing. This is why it takes several million sperm cells... to locate a female egg, despite the fact that the egg is, relative to them, the size of Wisconsin.
Sperm is a bandit in its pure state.
People forget we come from an embryo and we're part sperm and part ovary. We have both sides in us.
In the seventeenth century, it was held by some that inside a human sperm there was a minute human being - a homunculus - that was planted inside the womb. Development consisted of the miniature homunculus enlarging and passing through birth and on to maturity-just like inflating a balloon.
Although each egg cell produced by a woman carries a single X chromosome, the sperm cells produced by a man carry either an X or a Y. This means, in very simple terms, that the sperm cell determines a baby's sex.