Incredible Human Machine Page #7

called extracellular matrix, or ECM,

that has the power to regenerate tissue.

Suck away the cells

from just about any tissue in the body

and ECM is what will be left.

Mother Nature's done a really good job

of bringing this material together.

Stephen Badylak of Pittsburgh's McGowan

lnstitute for Regenerative Medicine

helped discover ECM's power,

which, like stem cells, has the potential

to heal many tissues in the body.

The real magic of the material,

if you wanna call it magic,

is that this is loaded with signalling molecules

that instruct the surrounding cells and tissues

to heal in a specific way.

So if we examine...

The best part is that extracellular matrix

is found in all animals.

Pig ECM, for example,

is not that different from human ECM.

lt's not that much different than a mouse

or a dinosaur's as far as that goes.

Therefore, when we take ECM from one species

and put it in another,

it tends to be accepted as self.

We can even extract the material

from one tissue, like pig's small intestine,

and put it into another

like Mark Kramer's shoulder.

We're going to have graft, tendon

and then more graft.

This is what l refer to as a taco repair,

simply cos it looks like a taco.

Basamania simply wraps the material

around Mark's damaged tendon

and sutures it into place.

Mark's own cells will then attach to the graft

and then within weeks his own body

will reconstruct the tissue and heal itself.

For me this is very satisfying

to go from a flimsy material

to now he has what looks like

a very nice healthy-looking tendon.

Oh, he'll be back in the gym before too long.

Extracellular matrix has already been used

to grow and treat things

like the oesophagus, skin, bladder.

Even to heal the damaged dorsal fin

of a dolphin.

This idea of coaxing the body to fix itself

may offer a whole new way to treat disease.

Salamanders and newts and starfish

can regrow entire legs. Why can't we do it?

Our goal is to tell the body,

''We don't want you to just heal this tissue again.

We want you to reconstruct this tissue.''

Perhaps one day we will grow a new arm

or leg as easily as a wounded starfish does.

For now,

we're stuck with the limbs our parents gave us.

And as the sun sets on our day,

just getting two incredible machines

to reproduce at all is challenge enough.

( Violin plays a tango)

lt's a simple biological function.

The swapping of genetic material

to improve the adaptability of the species.

But getting together is anything but easy.

The seduction.

The courtship.

The commitment.

lt's all part of an intricate dance

originated millions of years ago

and choreographed over countless generations.

So why all the fuss?

Why don't humans simply do

as an amoeba does?

Just split in two.

lf all we wanted was to make exact copies

of ourselves that is exactly what we would do.

But humans,

along with practically the entire animal kingdom,

want more out of life than to simply survive.

We're built to thrive

and mixing up genes through sexual

reproduction is the best way to do it.

The dance may begin with an attractive sight.

A smell, a touch.

Soon enough the heart beats faster,

blood pressure rises.

Breathing accelerates.

Skin gets flushed.

And whether or not baby-making

is on the agenda tonight,

the baby-making machinery is raring to go.

Every second of every day,

a man produces more than 1,000 sperm.

That's 60,000 sperm per minute

or 1 4 million during the course of an evening.

They may only be about two-thousandths

of an inch long,

but 300 million are always ready

to fulfil their life's mission -

to fertilise...one of these.

Unlike a man, a woman is born with her

allotment of sex cells, about one million of them.

Only about 400 eggs will ever get released,

less than half the sperm cells

a man produces every second.

Once the egg is pushed out of the ovary

each month,

it's swooped into the fallopian tube

for about a day,.

life's window of opportunity.

lf no suitor appears the egg dissolves.

But far more interesting is what happens

when one does.

Of the millions of sperm

engaged in this genetic race

only a few will defy all the odds

and glimpse the finish line.

And as the body's smallest cells

meet the largest, only one will make it across.

There was a time just a few centuries ago,

when some scholars believed that every sperm

cell had a fully-formed miniature person inside

called a homunculus.

(Babies laugh and gurgle)

We now confidently know this is not the case.

Deep within each of the body's 1 00 trillion cells

is a complete blueprint for a human being -

a genome.

Here our DNA molecules are tightly packaged

into bundles called chromosomes.

Each cell has 23 pairs of chromosomes.

Sperm and egg cells, though,

only have half a blueprint each.

They need each other.

And during that fateful meeting, their DNA fuses,

mingling the mother

and the father's genetic traits.

For several days, the fertilised egg journeys

through the fallopian tube towards the uterus,

growing and dividing along the way.

About 20 hours after fertilisation,

it divides into two cells.

ln 48 hours, four. 1 2 hours later, it's eight cells.

And by 72 hours, it's 1 6.

Each of the new cells

is genetically identical to the original.

At this stage everything from eye

and hair colour, gender,

and even to some extent height, weight,

intelligence, sense of humour and personality,

are all pre-determined.

ln fact, scientists can even sift through

a dish of embryos to choose gender

or identify genetic defects and remove them.

But not if couples have a baby

the old-fashioned way.

By the end of the first week, the free-floating

ball of cells, now known as a blastocyst,

has entered the uterus.

Cells continue to divide here

before they find a place to settle.

lt's official,. she is pregnant.

As the weeks pass, cells start to specialise

and forms begin to take shape.

At three weeks a groove marks the beginning

of a nervous system,

the top of the tube destined to become a brain

and the lower portion the spinal cord.

By eight weeks,

almost all of the organs and systems

in this walnut-sized embryo are in place,

earning it by week nine the official title of foetus.

And now growth really kicks in.

By 1 2 weeks, just as expectant parents

get their first glimpse into the watery womb,

the foetus may practise breathing,

taking in amniotic fluid instead of air.

Already it can punch and kick.

At 1 4 weeks, it can swallow and suck its thumb.

(Woman laughs)

By 24, it can hear.

By 32, it responds to music, voices.

OK, so that's... Oh, there's her eyes.

That's eyes, nose, mouth.

Now her mouth is wide open.

And at 40 weeks, give or take,

it's ready to enter the world.

Push.

- Ten, nine. Ten.

- (Exhales heavily)

- That's it.

- Now push.

Great, great. Great, honey.

Another push.

- Oh, my God.

- There's your baby.

Good job!

22:
30.

- Oh, my God.

- Good job.

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