Sperm: 15 crazy things you should know
Some want to kill sperm cells. Some want to buy or sell them. Some fret over their failure to get the job done.
Why can't we just appreciate sperm for the amazing little wrigglers that they are? After all, without sperm, the world would be a very lonely place.
So here are 15 fascinating facts about sperm, from Dr. Craig Niederberger, professor of urology at the University of Illinois at Chicago.
Abnormal Sperm? That's Normal
It's the price of monogamy, Dr. Niederberger says. "For those species where more than one male's sperm can find itself in a female at the same time, the sperm are much more uniform in appearance," he says. "In humans, Joe and Sam's sperm don't usually find themselves in Betty at the same time."
Half a Teaspoon
Sperm Wear Hard Hats
Well, not really a hat but an oval-shaped structure called the acrosome. It contains strong chemicals that are released once the sperm attaches to the egg. The chemicals melt the egg's outer surface, drilling a hole so that the sperm can penetrate the egg to release its genetic cargo.
Sperm vs. Semen
Sperm cells - which are made in the testicles - need lots of high-octane fuel to whip their tails. Lucky for them (and us), sperm get the fuel they need in the form of sugar fructose, which is supplied by the seminal vesicles.
Fluid from the prostate contains chemicals that cause semen to liquefy once it's inside the female. Without it, sperm would be locked in place and unable to swim.
One Testicle Is Enough
Lance Armstrong, shown here, is perhaps the most high profile person to have lost a testicle to cancer. He has fathered five children since then, three from banked sperm, but two, he says, were concieved naturally.
200 Million Competitors
The Factory Never Closes
As men age, their sperm may become a little sluggish and their DNA a bit more fragmented. But the factory never closes.
Hope springs eternal.
Sperm Are Tiny
Of course, what sperm lack in size they more than make up in sheer numbers. If a guy could coax all the sperm in one ejaculate to line up end to end, they'd stretch six miles.
That's a lot of sperm.
Sperm Need Protection
To keep immune cells from wiping out "invading" sperm, the testicles employ specialized cells to surround them with a sort of "picket fence."
Dead Sperm Can Make Live Babies
Which Way Do We Go?
But because so many start their journey, plenty make it to the egg. And that's despite the fact that the tubes connecting the uterus to the ovaries contain tiny hair cells that beat against the sperm.
Ever seen salmon swim upstream? It's a bit like that.
Sperm Live for Days
The Y Stands Alone
In fact, a man's Y chromosome looks just like his father's and his father's father's, and so on, back through the generations.
Refrigerator Testicles
A man's body keeps the ideal testicle temperature with radiator-like veins that pull heat away and muscles in the scrotum that raise and lower the testicles to bring them closer to the body's warmth - or farther away.
If a guy crosses his legs, his scrotal temperature increases by about 2 degrees. Ditto if he wears briefs. But lots of guys who cross their legs become dads, and Dr. Niederberger says the idea that wearing boxers will help boost fertility is probably misguided.
Two Months to Make Sperm
"Sperm are being started all the time, just like an assembly line," says Dr. Niederberger. "You don't wait for a truck to finish the assembly line before starting to build another, right? But just like an assembly line, it takes time to go from the start to the end."
So get busy.