A man and woman in love.
They embrace.
In 40 weeks she will give birth to that child.
In 40 minutes he will ejaculate.
His sperm will travel a total distance of 40 centimetres from his testis to her ovaries.
Tonight, I will dissect a man and a woman to show you that epic journey.
A new human life begins when a human sperm meets and fertilisers a human ovum,
that is a human egg.
But for this to occur,
the sperm has to travel almost the whole distance to the place where the egg is made.
The first part of its journey happens under jet propulsion.
But for about the last third of the journey it has to make using its own energy resources.
The race is on, and this is a race with 300 million competitors.
The reproductive system is situated in the small pelvis.
To understand that better,
I have bisected this gentleman in two halves
and when we look now on the cut surfaces,
then we can follow the way of the sperm,
here from the testis, up here, going through the abdominal wall and in here,
below the urinary bladder, through the prostate,
we see here the urethra going its way out of the penis.
To show you this, over on our live specimen.
Well, the internal and the external reproductive organ is quite hidden,
more in the woman than in the male.
But there is good reason why we see more in the male,it is the testis.
And the testis needs a good temperature,not too cold, not too warm.
Therefore, there is a regulation.
When I touch now, his surface, here of the thigh, you see?
The testis goes up.
Now let's see how this looks at the real specimen.
For that reason, we have prepared a body of a man and a woman.
Let's start now, to dissect the man.
When our specimen I like now to open the scrotum.
This is a part of dissection that always makes people wince,
but you'll be glad to know that no matter how long you have been doing anatomy or pathology,
it still makes you wince.
And the skin is rather thick,
because it contains those small, smooth muscle fibres,
which actually contract the scrotum
and are able to bring the testes close to the abdomen,
in case, for example, when you jump into cold water.
But now I am already isolated the testicle
and the testicle is surrounded by a number of small tissue layers,
which by now I have to open.
The testicle has two main functions,
obviously its main function is to produce spermatozoa.
And as I said just now,
there are approximately up to 300 million spermatozoa per ejaculate,
so that's an awful lot of spermatozoa in a lifetime for a man.
Its other function is, that hidden amongst the tubules which make the spermatozoa,
are hormone secreting cells
and the testis is also responsible for producing testosterone,
the main male hormone.
So I remove now, those tissue layers
and what you see is a quite dense tissue layer,
because within the testis there is this pressure, higher pressure,
therefore it is necessary that it is surrounded by a dense tissue.
So we see here now, the testis
and around here, the so-called epididymis,
where the sperm, which is generated here
and I will show you by opening, now, the testis.
For a man it is really a strange feeling.
Okay, and this is the place where the sperms are generated within the seminal ducts.
And here, we can just see one of those ducts.
The testis is a lobulated structure.
It is made up of about 500 individual tubules called semeniferoustubules.
And two of them I just take out
They are almost as thin as a spider's web.
These are about 0.2 millimetres in diameter.
But they can be up to 70 centimetres in length.
So it is like the testis is packed with these hugely long, but very narrow tubules.
And down the middle of these tubules is where the sperm are produced.
If we could just have the monitor back in again.
We can see here again, the sperm wiggling around.
Each sperm has a tail that you can see wiggling
and these little bright dots are the sperms' heads.
Each sperm's head is only about four micrometres,
that is four thousandths of a metre in diameter.
It means you can line up 500 spermheads on a pinhead.
And each one of those heads has enough DNA
to contribute half of the new material to a new human life.
Now let's follow those sperms out of the tubules.
They go in here, into what is called the epididymis.
The epididymis, yes.
The spermatic, the semeniferous tubules, form, as I say, these several lobules within the testis.
They then go into a net,
but it's a strange fact that when the sperm exit from the testis,
if you take sperm directly out of a semeniferous tubule,
they are actually not able to fertilise an ovum.
These are non-enabled spermatozoans.
And they pass from the testis into this,
through a network,
into the structure called the epididymis,
which if it is fully unravelled, can be several metres long.
And it is within the epididymis that the sperm mature
and become enabled to fertilise an egg.
And I just follow, now, this storage site of the sperms here,
this big hat, down here into the pathway to the prostate
and later on, the penis and even running in a zig-zag way.
This is called the ductus deferens.
That's right,after the sperm have been stored in the epididymis,
they then pass into the vas deferens,
which conducts the sperm from the testis towards the penis.
So I will now go up here, follow the way
and you see as, together with this tube, a lot of blood vessels go down to nurture the testis.
And I go up here to what is called the inguinal ring,
actually about here, the funiculus spermaticus,
this whole bundle of ductus deferens, as well as the veins, arteries and nerves.
They enter just here now
at a place which we call the outer inguinal ring.
The testis has an interesting history.
It actually develops inside the abdominal cavity.
And during development and usually by a few years of age,
it drops down from the abdominal cavity into the scrotum,
which is where it spends most of the time.
It has got a clever structure, this canal that it comes out through,
because if the testis simply came out through the abdominal wall and made a hole,
the pressure of the intestines inside the abdomen might be able to push them out through that hole.
So, in fact, the way it is constructed,
is that there is a staggered hole in the abdominal wall,
so that the inside and the outside don't lie over each other.
And this allows the musculature of the abdominal wall to close-off that space
and keep the abdominal wall strong and prevents hernias developing.
It is, however, the weakest point of the lower abdominal wall in the groin
and it is the commonest places where hernias do develop,
because they sometimes manage to dilate the so-called internal ring,
push along this canal and come to the outside.
So the fact that our testis has actually taken this course during embryology,
means that we are left, in the male, with a slight weak point in the abdominal wall.
Well over here we have a cross-section of the vas deferens.
And let me first remind you where we are again,
because these names are slightly confusing and all these parts have names
that none of us really know unless you have learnt them.
The vas deferens is the tube that takes the sperm from the testis,
up, round, through the abdominal cavity and out to join the penis.
And this shows a cross-section of the tube.
A cross-section is when you have a tube and you cut across it like this.
So we are looking end-on at the tube here.
And you can see that the vas deferens is quite an impressively muscular structure.
It actually has three layers of muscle:
an outer one here,
a middle one here
and an inner one here.
And you can this crinkled inner space, here, is the lumen of the vas deferens,
the space which dilates up when the sperm go past.
The vas deferens is one of the main motor organs for pushing the sperm to the outside world.
And we will come back to that a little bit later.
But the fact that the testis dangles down into the scrotum,
has a strange consequence.
It is dangling down on a pedicle, a rope,
made of the vas deferens and the nerves and blood vessels that support it.
And sometimes this has an unexpected and dangerous consequence.
It actually turns around and this way blocks the blood supply
and in order to save the testis, must operate it at the same day.
That's right, normally the testis is quite well attached in the scrotum,
but if it does manage to move,this is a medical emergency,
as you can imagine, when you cut your blood supply off to any part of the body,
it starts to be in trouble quite quickly.
And if a torsion of the testis isn't untwisted within an hour or two,
that testis actually infarcts,it dies and then is no use for reproduction.
If this happens, there is often a precaution taken
that the other one is fixed in the scrotum so that that can't happen.
In this vas deferens travelling up here,
it is very clear to see that its main arteries with veins and nerves,
all together travelling up here, entering the abdominal wall.
Well, let's see where we have got to on our live model over here,
we have our resident anatomical artist Juliet
and our live model today, Michel.
And Juliet is drawing on Michel here,
the tubing that we have just been describing.
It is actually a little bit difficult to demonstrate this tubing on a live model
because it is in quite a small area and it is quite complicated,
so we have simplified it slightly here.
And what we are seeing is the vas deferens coming up from the testis,
through the groin and
this curve here is going to be looping back through the abdominal cavity
and behind the penis, behind the, into the prostate gland
and joining the seminal vesicles to make the ejaculatory ducts.
This is actually located a bit lower down than shown here
and behind the penis, but we have to show it like this,
otherwise you wouldn't actually be able to see it.
Well, let's rejoin the journey, then
and follow the vas deferens into the abdominal cavity.
The vas deferens here,
along with its main arteries and the veins and the nerves,
going here to the outer inguinal canal
and the inguinal canal starts actually here, I cut it now open.
And exactly from here to here,
the inguinal canal is seen as it moves through the abdominal wall in an oblique way.
What we do, have now to do, to open the abdominal wall,
all along to the other side, take the tissue flap down
and look the further way how the vas deferens actually approaches the prostate,
finally reaching the urethra.
You may be wondering:
'why is it that the vas deferens takes such a strange up-and-down route,
why does it loop round in this way through the abdominal cavity?'
And the answer being, is that this, as I say,
recreates the journey that the embryological testis took,
the developing testis took,
as it descended from the abdomen.
And it is the result of the fact
that the testis has to drop into the scrotum from inside the abdomen
that gives rise to this rather long-winded route round,
when we trace the full journey of the spermatazoan.
So, by peeling back the abdominal wall here,
we should now be able to find the spot where the vas deferens moves inside the abdomen,
through the inner layer of the abdominal wall.
What you see here, this is the so-called peritoneum,
this very faint tissue layer covering the abdominal contents from the inside.
The red that you can see here inside of the abdominal cavity
cavity is part of the embalming process that this body has been put through.
This wouldn't normally be there.
So we take this red off.
This is a polymer, an injected polymer, rather than anything else.
In order, now, to follow the vas deferens,
I have to flap back the small intestine and cut the pubic bone.
So the human body is made out of pretty stern stuff
and it's not actually constructed to be disassembled.
Certainly some of these tubes take convoluted courses around bones
and between bones and over other organs,
so it makes actually doing a demonstration of certain areas quite challenging
and this is, indeed, one of those areas.
But we thought it was worth trying to demonstrate the full course of the tubules to you.
I will take now out the cut pubic bone,
with the penis and all the internal male genitalia out here
and Marius I need, thank you very much,
a need a separate table to dissect it.
It was difficult to take this piece of tissue out because a lot of fat
and in addition a very large urinary bladder.
And just behind this urinary bladder,
as you see from the testis,
the vas deferens runs behind the urinary bladder.
I have to remove the peritoneum here, here
and where the vas deferens goes behind the urinary bladder,
which is actually this, we expect the seminal vesicles,
just at the back of the urinary bladder
and there, actually they are coming out.
And this what I have here in my hand is a rectum.
So I take the rectum away and I think this is a good decision,
because here now, you see much better than I even expected, the seminal vesicles.
I take away a little bit of the connective tissue
and here is a typical glandular tissue of the seminal vesicles becomes obvious.
And they are quite large in volume.
And the amount of secretion, they give for the ejaculate is not minimal.
So I think it might be helpful,
while a bit of further dissection on that specimen takes place,
to come over to our live model again
and just to remind ourselves where all the tubes are,
because this is quite a confusing region of the body.
So what we have done so far is trace the vas deferens from the testis,
up through the inguinal canal back round into the abdomen,
back down and we are now reaching the prostate gland which is behind the penis.
And I have here a plastinated model, which may help to make that clear.
On the plastinate, if you look from the side,
the vas deferens is this tube that loops across the entering ureter into the bladder
and then goes down behind and underneath the bladder.
And it enters this lump, lying below the bladder,
which is the prostate gland that has been drawn on here.
And just sitting on top of the prostate gland,
is a blind ending diverticulum, called the seminal vesicle.
And there is one on each side, there is two seminal vesicles
and the vas deferens loops over, joins the seminal vesicle
and then they have a very short duct that opens into the prostate gland
and that duct is called the ejaculatory duct.
Now, it is an interesting fact that the seminal vesicle makes about 70% of the ejaculate.
And the rest of the ejaculate, most of the rest of the ejaculate, is made by the prostate gland.
Some of the ejaculate comes from fluid in the vas deferens and the epididymis,
but only about 2% of it is actually sperm.
Most of the rest of it is these other fluids which nurture the sperm,
coagulate the semen so it can't come out again after it has been passed into the woman
and make sure that the sperm are fit for their journey up to meet the egg.
After taking the fat away,
after removing the connective tissue,
the specimen shows much more clarity.
The sperm, originating here in the testis,
going along the vas deferens,
approaching the prostate gland, which is actually here.
Maybe just worth saying at this point,
that the prostate gland and its position below the bladder
is one of the problems with advancing age.
Here I have a plastinate of the bladder and the normal sized prostate gland.
And it is very common with age that the prostate gland undergoes hyperplasia,
an enlargement that occurs in many men with increasing age.
It can be a problem, because the urethra from the bladder
has to pass through the prostate gland to get to the outside world.
So the hyperplastic prostate gland can actually press on the urethra
and prevent the urine getting to the outside world
and this is the cause of urinary retention
and also a cause of urinary infection in men,
because the urine can pool behind the enlarged prostate gland.
I have cut open now be urinal bladder.
I believe it holds about 400 millilitres.
And when I hold it up now,
then you see that exact below this urinary bladder,
there is a prostate.
And the prostate is connected directly with the penis.
Prostate - penis.
And the penis actually consists out of three parts.
This is a slice through a plastinated penis.
And you see there are two erectile tissues,two parts of the penis,
the so-called cavernosa, corpora cavernosa.
And here you see a third part of the penis,
which is a spongeous tissue which doesn't erect as much those other parts
in order to leave space for the semen to run through at the right moment.
Now, let's see now where those three parts are on the real penis.
Here, actually, the lower part.
Here the lower part, the part where the urethra goes through
and you see that half of the penis is actually inside the body.
It is attached especially in those two parts, to the penis to the bone.
And actually, those parts here,
which I now take around by my instrument,
this part of the penis goes from here, up here and attaches to the bone.
This is the bone, is the pubic bone.
The attachments to the bone are very firm and fibrous,
so that when the erectile tissue in the penis fills with blood,
the penis does point in the direction that those quera are pointing,
which is the direction of erection.
And to prove that,
I will now do longitudinal incision into this erectile tissue.
When I cut in here
One moment
This is never an easy thing to watch.
Then you see really that here, everywhere there is this black tissue,
which shows that the clotted blood, inside
I think you don't get used to this procedure even if you are an anatomist.
More important now,
we look at the opening of the penis and we take just the worst away of the sperms.
I take a probe and I enter here.
I go all the way down here, through the prostate
and inside the prostate,
the urine from the vesicle, urine area
and the vas deferens meet
to find their way to the outside world.
That's right, so the ejaculatory ducts,
which were formed by the fusion of the vas deferens and the seminal vesicles,
enter the middle of the prostate gland
and through the middle of the prostate gland, forms the urethra.
And there is a small swelling on the urethra in the mid-part of the prostate gland,
where the ejaculatory ducts enter
and then the semen goes out through the rest of the prostate gland
and down along the penis to the outside world.
And more obvious,
where everything is in proper position.
Down here, the penis starts within the body.
So, everybody who is not satisfied with the length of the penis
be reminded that double the length you don't see.
So it is in here.
Here, the urinary bladder, below the prostate gland.
And from the testis, coming up through the vas deferens,
together with the seminal vesicles, entering the prostate
and finally bringing the semen out here, at the opening of the urethra.
So we have now traced the full journey of the sperm
from the testis to the end of the penis.
But before the sperm can actually exit into the woman,
there is actually one more thing that we need to talk about.
This is an extraordinary specimen.
What you see here is the arteries injected by polymer,
after the curing of the polymer.
All of the tissue has been taken away except of some bones.
When you inject the specimen, especially here in the arteries of the thigh,
large pressure is build up
and therefore for fixation, it is not unusual that the specimen,
as in this case, got a post-mortal erection.
The penis contains these two large bodies of erectile tissue,
the corpora cavernosa on each side of the penis
and when an erection takes place,
basically what happens is that for a short period of time,
more blood flows into the penis than flows out.
So, effectively, the spongy tissue is blown up like the balloon
and that causes an erection.
This then puts the penis in a position to transfer the sperm to the woman.
We don't normally think of blood as having a hydraulic function in a body,
we normally think of it is carrying the oxygen round the body,
but without this particular hydraulic function of blood,
we wouldn't be able to naturally reproduce.
Let's have a look now, here, how this would really work.
This is a plastinated penis, with testicles and urinary bladder.
It has to be erected to go here inside the vagina.
And here, in working position,
it gives off the sperms just in front of the mouth of the uterus.
This image we have here is quite a remarkable image.
A man and a woman were persuaded to make love in quite an unusual place,
in the middle of an MRI scanner.
And this is actually a cross-section through a male body
and a female body in an MRI scanner
and it shows an erect penis in the vagina, delivering sperm,
well, where the sperm will be delivered, to the uterus.
To get to this point in human reproduction, requires a complex neural sequence,
both psychological and pelvic.
And in the actual moment of ejaculation,
that neural sequence ensures that a contraction wave passes up the vas deferens
at the same time that the seminal vesicles contract,
that the prostate gland contracts,
that the urethra nearer the bladder contracts to stop the ejaculate going the wrong way.
So the ejaculate is propelled up the erect penis
and delivered to the top of the vagina,
near the cervix uteri, near the entrance to the uterus,
which is where the sperm has to go next.
And now at a time the sperm actually are inside the female genital tract,
within the vagina, it is time to change the body.
Let's dissect, now, the female body.
I want to show you first at the model where it is actually situated.
So this is the external female genitalia,
with the small labia,
with the introitus for the vagina.
And just here you see the hymen in this specimen.
And it is situated about in this way.
All this from here up, below and behind the bladder
the uterus, the ovaries, all the structures are called the internal female genitalia.
More interesting than external, because we see them more rarely.
Now I would like to show you that on a live specimen.
Alexandra could you come in.
Thank you.
And to put it, to project it into her body,
here is the urinary bladder
and just behind, the uterus.
And I want to show you more clearly,
Marius,
to show you this in the cross-section.
And here, the real specimen in a slice,
it would look like that, with the uterus and the bladder here.
But more clear it all becomes,
when I take a horizontal section through her pubic region
and when you look at it now, we see.
Here the bone, the pubic bone
and as in the male, the clitoris here is attached to the bone,
here is the tip of her clitoris.
Behind the clitoris, there is the urethra.
And here at the end, at the back, the rectum,
the large part of the bowel, the anus and this is the sphincter around the anus.
In between anus and urethra, there is the vagina.
And you see very clearly,
it is not an open tube,it is closed
and it close in order to be able to expand when the penis enters, like an H.
So I would like to demonstrate this with a very simple paper model,
also an H shape.
It is closed
and in special occasions, the penis goes in
and the vagina is open, ready to take the sperms at its end.
So thank you very much for the demonstration.
Now we should go to the real specimen.
I start dissection.
We will approach the female pelvis in the same way as we did in the man,
with the incision around the lower part of the belly,
to have access from above into the small pelvis.
Another point that one could make about the vagina
is that it has to be able to receive the penis.
And to do that, it actually has its own special lubricating gland,
known as Bartolin's gland.
It actually looks rather like a salivary gland.
There is an important difference between the male and female abdomen,
which sometimes isn't appreciated.
The male abdomen is a closed cavity.
We have shown that when the sperm move from the testis to the outside world,
they pass through the abdominal cavity, but in a tube.
On the other hand, in the female this is different,
because the sperm have to pass up the cervix uteri,
into the uterus, into the fallopian tubes.
At the other end of the fallopian tube,
the egg has to come from the ovary and enter the fallopian tube.
So, in fact, the female abdominal cavity does have an entrance to the outside world,
because it is, in fact, possible for fluid or bacteria
to pass right the way from the cervix uteri up to the end of the fallopian tube
and into the abdominal cavity.
And this is actually the route where bacteria can sometimes enter the abdominal cavity
and cause pelvic inflammatory disease.
I take now down this tissue flap with about three centimetres of fat
and I have to be careful not to open, accidentally, the urinary bladder.
So I have successfully opened now, the abdominal cavity
and we expect now the genital tract within the small pelvis
and therefore I have to flap to the top the small intestine here
and to find the uterus.
And I take the large intestine out, which I have just cut here
and I remove the peritoneum,
then we have here, the uterus.
I want to take this uterus with the external female genitalia out,
as with the man, as one block specimen.
So now let's do that, just take the knife and continue the cutting.
Yes, Marius I need now the tablet..
So..
The other specimen is.
And I like to come in front to demonstrate it.
All this is the external female genitalia.
And this, here, is the uterus.
From both sides, from the uterus, there are, here, the ovaries.
And the ovaries actually, they give off the egg by.. from the surface
and here, the fallopian tubes travel to the uterus to travel with the eggs.
So on this side, actually, this is the ovary
the egg jumps out here,
it is catched, here by the fallopian tubes,
travels into the uterus.
And fertilisation of an ovum actually occurs within the fallopian tube.
And this actually marks the end, then, of the journey of our sperm and our egg,
because once they meet, and fuse into a zygote,
in other words they start to make an embryo,
they then become a different entity, altogether.
The sperm and the egg have now vanished
and they have been replaced by a potential new human life.
Usually, that passes down the fallopian tube into the uterus for further development,
but if that doesn't happen,
development sometimes starts to happen in the fallopian tube, itself.
And when that happens, that is what an ectopic pregnancy is.
That can be very dangerous,
because the fallopian tube isn't designed to expand, like the uterus is.
If the embryo implants in the fallopian tube and starts to develop there,
usually the woman develops severe pain at about six weeks of gestation,
the fallopian tube ruptures and a severe haemorrhage can occur.
So, abdominal pain occurring in the first six to eight weeks of pregnancy
is a recognised potential medical emergency because this is what may be underlying it.
So what we have here is a cross-section of the fallopian tube.
What you can see is an external muscle layer and a convoluted space here.
Each of these spaces is lined with a layer of cells, with cilia,
which are like little fronds, which waft the fluid from the ovary down towards the uterus.
And those cilia pull an ovulated ovum from the ovary into the fallopian tube.
On the next slide we can actually see the human eggs in the ovary,
each of these is about 30 microns across,
in other words you can get 30 or 40 of these in a millimetre.
Now, it's a strange fact that by the time she is born,
most of a woman's eggs have died.
The foetal ovary and we have a slide of that next, contains many, many more eggs.
At its peak, the foetal ovaries contain about 10 million eggs.
By the time a baby girl is born, her ovary only contains about one million eggs
and by the time she reaches puberty, less than 1% of those eggs survive,about 40,000.
And of those 40,000 eggs, only about 400 will ever be ovulated.
So that means, only one in 25,000 of the eggs that are produced in the foetal ovary
ever have the chance to make a baby.
And it's an interesting question 'why should that be?'
And one standard textbook reason is that, it is difficult to make a good egg.
I guess another possibility would be that,
a long time in the distant past, we evolved from a fishy ancestor
and because fish live in the sea,
they tend to make thousands and thousands and thousands of eggs.
And maybe the fact that our foetal ovaries,
or a girl's foetal ovaries are full of eggs
is a distant memory of our fishy past.
So I think this might be a good opportunity
to look at where these organs are located in our live model, Alexandra.
And Juliet has drawn on here,
the vagina, the cervix,
the uterus, the fallopian tubes and the ovary.
So, the sperm that are deposited by the cervix uteri have passed up through the uterus
and out along the fallopian tube,
where they have encountered an egg, moving down the fallopian tube.
Their journeys stop where they meet and where fertilisation takes place.
In spite of the fact that many millions of sperm may actually reach this place,
only one manages to penetrate the egg.
That embryo then passes back down the fallopian tube
and is located and begins to develop, in the uterus.
So now I think we can go and open the uterus, back on our dissection specimen.
So this uterus may be pregnant.
This could be about the 10th week of pregnancy.
Now I come to a very difficult procedure.
So the aim, here, is for the knife to pass through the uterus
in such a way that it intersects with the uterine cavity,
so we can see a full midsection of the uterus.
And not to cut a possible foetus in two halves, I stop here now and have a look.
Well, give me a small knife.
So I want to be very careful to take this polymer out,
which we injected together with the fixative, the formalin,
to avoid putrefaction, into the blood vessels
and be very careful whether we will find here,
possibly, certainly not a healthy but, a kind of failed pregnancy.
But what I see here is just tissue.
I think it's probably worthwhile saying as well,
that the size of normal uteri does vary substantially in women.
After the menopause, the uterus tends to atrophy.
And postmenopausal uteri can be quite small,just a few centimetres big.
But in the childbearing ages,
especially in women who have previously had children,
the uterus can vary in size from eight or nine centimetres to 15 or 16 centimetres.
So, I think in the absence of any definite evidence of pregnancy,
this uterus seems to be within the normal range, I would suggest.
And now we like to see a real foetus, how it develops.
Will you bring it over?
They originate from old anatomical collections,
in formalin which I plastinated.
This foetus is probably of the order of five or six months old.
The organs of the foetus are pretty much fully developed by about three months.
And thereafter, there is a process of increasing in size
until the foetus is mature enough for birth.
One of the features that one often notices about premature babies is their,
if we could show the face of this foetus,
is a rather little wizened old-man faces.
And this is because the subcutaneous fat
is actually one of the last things to develop on a foetus.
So premature babies often have an older-looking face,
mimicking the lack of adipose tissue you often find in older people's face.
And this is the time for the audience to ask questions.
Please.
Thank you. If a woman is pregnant with more than one child,
say identical twins, as I am,
how does the umbilical cord work?
Is there there is one connected to each baby,
but does it go up to just one into the mum,
or how does that go?
Because if she has got 3, 4, 5, 6 are their 3, 4, 5, 6 umbilical cords?
Well, one way that twins can happen
is that two ova that have been fertilised enter the uterus and implant.
And in that circumstance, usually what happens,
is that they have two separate placentas.
But another way that it can happen is that the one zygote,
the one embryo that has come down from the uterus,
splits into two at an early stage of development.
And in that case, although the individual foetuses have separate umbilical cords,
they may share a shared placenta
More questions ?
How to medicines such as Viagra or Cialis work?
Medications like Viagera or Cialis, they act on the blood vessels,
actually, they prevent that the blood prematurely moves out of the penis.
When there is a blockage out and more blood comes in, the penis is in good shape.
Okay, more questions
I noticed when the testicles were...was removed from the scrotum
that there was a sticking...it was adhering a bit.
Were those adhesions, is that normal, is the testicle usually looser in the...
It is very normal that the testicle is attached to the scrotum in order to prevent torsion.
The connective tissues in a fixed specimen tend to be thicker and firmer
than in a fresh specimen.
So, in life, the testis is actually slightly more freely mobile within the scrotum
than in a fixed specimen
But if there is some kind of adhesion,
wouldn't there be a sensation when the testicle moves up-and-down?
I should imagine that there would be, yes,
because it will pull on the scrotal skin, yes.
And this, actually, is the right time to complete our journey by giving birth to a child.
The child develops within the abdomen of the woman.
And this is the pelvis, the abdomen is above.
The uterus is below here and it comes out during the pregnancy.
At the time of birth,
the head of the foetus just is atop the small pelvis.
And in order to get through, it has to move several times.
Because this is an oval shape
and the head is oval in this way,
the first change, the first turn,
is the foetus, the baby now,
is doing it around to the left, parallel.
And then going in,
the outside is oval, in this way.
So we go in, here
and now we have to go, turn again
and then it turns in here
and goes and the shoulder actually moves in the oval, diameter
and when we go out here,
we turn around here again to bring the shoulder out.
So do it again very fast, as it should happen in nature.
First turn,
second turn,
third turn
and birth is done,a new generation has started.
Transcript: bigbreaths Synchro: PyrSos_