1. The Majority of Sperm is Abnormal
Humans aren’t great at making sperm. In fact, over 90 percent of any given ejaculation is malformed. As monogamous animals our sperm does not have to be perfect since the sperm is typically not competing against another person’s sperm.
2. Sperm Factory
Although there’s a large turnover of sperm, the latest studies suggest that sperm takes more than two whole months to form.
3. Mister Acrosome, Tear Down This Wall!
Sperm wears a helmet that allows it to fertilize the egg. The helmet is called an acrosome. When the sperm hits the egg the acrosome releases chemicals that melt the surface of the egg so that the sperm can enter.
4. One Testicle is A-OK
If someone is born without a testicle, or there is an accident, that person can still conceive. In fact, the other testicle usually grows in order to compensate. Lance Armstrong has had two naturally conceived children since he lost a testicle to cancer.
The Y chromosome is the chromosome that makes a male a male. Every other chromosome in the body is a combination of your mother’s genes and father’s genes, but the Y chromosome cannot be mixed. So a male’s Y chromosome is identical his father’s Y chromosome, and his father’s Y chromosome, and so on.
6. Can’t Stop, Won’t Stop
Women are born with all the eggs they will ever have and usually in their middle age they’re done being fertile. Men, on the other hand, are always producing sperm. Of course, the quality of the sperm does degenerate a bit with age.source
7. Unknown Intruder
Created late in human development, or puberty, sperm cells could be attacked by the immune system because they are unknown. Luckily, there are cells that surround and protect the sperm so that they aren’t attacked.
8. The Sperm is Just the Vehicle
We often think we’re a sperm/egg combination that grew. But the sperm is irrelevant. Researchers kill the sperm when creating test-tube babies and then they inject the dead sperm into the egg. The DNA inside the sperm is the only thing the egg needs.
9. Stay Cool
For the sake of the fragile sperm, testicles have to stay about seven degrees cooler than the rest of the body. That’s why testicles hang outside of the body. When testicles shrink in the cool weather it’s just to get more body warmth.
10. The Entire Population of Brazil
Each ejaculation is only about half of a teaspoon. Not much, right? Actually, there are 200 million sperm in each ejaculation and all of them are competing to fertilize the egg. That’s two-thirds of the population of the United States!