Every day around 350,000 babies are born.
Each one - utterly unique.
A few months ago this baby didn't even exist,
and the story of how it came to be against impossible odds
This is the moment of conception.
When one single sperm fused with the mother's egg.
If another sperm had got there first this baby would be someone else.
So what made that winning sperm so special?
Why did it succeed over billions of others?
To find out, we are going to take you on the epic journey sperm undertake
through the human body.
And we're going to do it by scaling the whole thing up to human size.
For the first time we will be able to appreciate
just what an extraordinary journey sperm face
as they try to reach the egg.
It's one of nature's most spectacular stories,
and it's the reason you are alive.
The sperm will face death that every turn.
There is no going back.
And only one winner.
Like most average men, Glen has no idea about the miracle of engineering
tucked away in his pants.
Glen's testicles, hanging freely to be three degrees cooler than the rest
of his body, are producing 1,000 sperm with every heartbeat.
And it's this tiny world of frenetic activity that fascinates the world
of reproductive science.
Sperm are quite unique because
they are free-living cells.
They almost have a life of their own.
They have but one aim, which is to deliver
the genetic payload from the male
to the female through a really quite complex
series of environments, both in the male and female reproductive tract.
Sperm move all over the place
and they like certain things,
they don't like certain things.
They are very smart little creatures in a way and they are a lot of fun
to watch in a Petri dish because they are constantly in motion.
And the fact that it's occurring at the microscopic level means that,
as scientists, we have a great deal of difficulty
studying it and observing it.
A sperm is just 1/500th of a millimetre long.
So to make things easier,Dr Allan Pacey and a team of experts
have agreed to help us scale up them and their world 34,000 times.
Along the way they'll give us practical advice on how to give sperm
the best chance of reaching the egg
or what kind of sex to have and when to have it
to maximise the chances of conception.
The first thing we asked our experts was quite simple.
In our people-sized sperm world what would a testicle be like?
The testicle is a...
roundish, oblong structure.
If we cut it in half, cut thin layers through it and looked at it
down a microscope we would see a series of tubules that you might
liken to floors of a building.
If we were to take a sperm and
scale it up to man-size
you would have to find a building that was about 1000 metres cubed.
1,000 metres by 1,000 metres by 1,000 metres.
That done, we can go inside.
Waiting in our giant testicle,an army of freshly-created sperm.
Just like the real thing,our sperm are split by gender.
Half produce boys and half produce girls.
The information needed to determine the sex of a baby
is stored in a sperm's head.
Here,we find their genetic package.
23 chromosomes of DNA,including the key gender chromosome.
Either X for a girl or Y for a boy.
Situated just below the head,
an engine of energy producing mitochondria
that propels the sperms mighty tail through the female body.
There's many millions of sperm.
You could think of it as a very large office building where there's
lots and lots of elevators and
tons of people, maybe at rush-hour, all moving in different directions.
X and Y sperm are produced in almost equal numbers.
Boys are thought to be faster but the girls live longer.
Once created, each sperm ends up
in a structure on top of the testicle called the epididymis.
A tightly coiled six metre-long tube which can hold over a billion sperm.
Imagine being crammed into a dark, winding, 200 mile pipeline with no
idea when or if you'll ever get out?
It's here, with no inkling of the horrors to come, our sperm must wait.
Their fate now will depend on events unfolding in the outside world.
In contrast to the billions of sperm produced continuously in
A woman, like Emily,will produce just one egg a month.
Reaching it won't be easy.
The battle that sperm have
in order to find and fertilise an egg is just immense.
Everything is working against sperm.They are not really given
a helping hand by the female reproductive tract.
You've got hundreds of millions of cells
that are swimming wildly about.
You've got a lot of death, you've got a lot of obstacles to overcome.
They've got to make their way through a complex series of
environments in a kind of warfare.It is warfare.
So if conception is a war,this is the theatre of operations.
From a sperm's point of view,landing in Emily's vagina
is like D-Day.
Their first objective,whilst under non-stop
attack from the female immune system, is to reach a tiny opening high above
them at the back of the vagina.
From here, they can enter the cervix.
The terrain in the cervi is completely different.
This is a dark, treacherous maze of uncharted tunnels.
The sperm will need to find a way through to the uterus.
One wrong turn and it's a slow, lonely death.
In the uterus,Glen's sperm will be looking for
a doorway just a few sperm head wide
in a vast, sterile area where, once
again, Emily's elite defence force will be waiting to take them out.
Then it's on to meet the egg.Timing is everything.
Get there a moment too early or too late and you are doomed.
#ANDY WILLIAMS: Emily
# ..Of silver bells, coral shells,
Glen's sperm are just seconds away from participating in one of the most
enjoyable experiences the human body has to offer.
But what would it feel like to be propelled along a narrow pipe
covering 15 miles in less than two seconds, whether you like it or not?
For each individual sperm,this is a wet and wild, high-speed
one-way ticket to oblivion.
They are not swimming, they are being forced there
by muscular contractions and by peristaltic contractions.
From the point of view of the man it's a very pleasurable experience.
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