Adam Taylor

When I say a long way to go, seven meters.

Seven meters from the testicle where it's made to the woman's fallopian tube where it fertilizes an egg.

Seven meters is four times the height of the average American man, an astonishing distance for the tiny sperm cell.

And yet when you do the math,

things don't seem to add up.

I'll just explain the journey that sperm take.

They go from the testicle to something called the epididymis, which is a four centimeter long organ that sits on the back of the testicle.

Then into something called the vas deferens, which is the tube that's snipped in vasectomies, about 45 centimeters long.

then into the urethra, which is about 20 centimeters long.

From the man's urethra, they then go into the woman and travel about 15 centimeters inside the woman.

Now, what I've just explained adds up to about a meter, yet I said the journey was seven meters.

So there's an unaccounted for six meters.

And the answer to where that six meters is, is on the testis or rather the ancient Greek for this, which is epididymis.

And this incredible organ, the epididymis, may be four centimeters long.

But inside it is a miracle of anatomical engineering.

A tube so coiled so astonishingly tightly that it stretches for six meters.

So inside a four centimeter long epididymis, there is a six meter long tube.

and the sperm travel for about two weeks inside this six meter long tube and mature inside it.

They learn to swim, they learn how to fertilize an egg.

And so when they come out, spend out of the two weeks inside the six meter long tube, they are as it were mature and able to do the job that they were made to do.