Reproductive System Lecture Part 02

>> Okay. So these testes are covered by a membrane called the tunica vaginalis.
And like I said there's a outer, you know, parietal layer
and an inner visceral layer and in between there is a fluid.
Now deep to this membrane -- deep to the tunica vaginalis is another layer
and this layer is called the tunica albuginea and it's just --
it's made up of dense, dense or regular, dense regular tissue and it extends inwards
and it divides the testes -- excuse me.
It separates the testes and divides them up into lobules.
Just like we've seen lobules before in the liver, we've seen lobules in the lungs,
we've seen lobules in the thymus gland, etc. So likewise let's put here that we have deep
to the tunica vaginalis is a membrane that is called the tunica albuginea.
[ Pause ]
The tunica albuginea; okay.
And we'll put in parenthesis that it separates the seminiferous tubules, the STs into lobules.
All right.
So that's just a little bit about the external structure so if we look over here
and we look at the computer screen.
We can see some of the structures.
First of all, we see the testes right there and then we can see the --
this is what they look like, you know, if you take a section.
You can see that this is the -- one testis right here and you can see where it's covered by all
of its different layers and then this is what it looks like in a human cadaver.
You can see the testis here and the testis here.
So another view from the side and here's what we can see.
No, one more -- one more layer to see those layers.
So here we have the testes.
Do you see these tubes, the coral tubes?
These are the seminiferous tubules inside.
Can you see where they're being separated into lobules?
Okay. So that right there -- this membrane right here is the tunica albuginea
and then you can see here in, you know, kind of a pinkish color is the parietal layer
of the tunica vaginalis, and then right on the testis is the visceral layer just
like we've seen in all of our other organs and there's fluid in between.
So that gives you a little idea of putting all of those structures together.
Now in terms of the function of the testes, a couple of different functions are carried out.
And the functions include first of all, because they are primary reproductive organs,
they produce sperm and they're producing the sperm again in the seminiferous tubules.
That's where the developing sperm cells are.
And then they also -- the cells in between the seminiferous tubules --
those interstitial cells, those are the cells that make the hormone testosterone.
So we'll put here that the interstitial cells and I like the word interstitial cells instead
of the Leydig cells because we see once again our famous prefix that we'll see
on the final exam "inter" meaning between.
Between -- so in between the seminiferous tubules are the cells called interstitial cells
or again Leydig cells and these make the hormone testosterone.
And we'll talk about this at the very end of -- all of the functions of testosterone when we --
at the very end of our reproductive system lecture.
Okay. And then the cells that we call the sustentacular or the Sertoli
or the nursing cells, those are the ones that --
these cells, what they do is they provide a basic environment -- excuse me.
Not a basic environment, a protective environment for the developing sperm cells.
[pause] It's their cytoplasm, the cytoplasm of the sustentacular cells that actually helps
to nourish the developing sperm cell.
Now these cells -- these sustentacular cells are kind of interesting cells
because you know how we've talked about barrier before.
How we talked about blood barriers?
Do you guys remember where we had our blood barriers so far?
We had them in the brain.
Where else did we have a blood barrier?
[inaudible response] I'm sorry?
[inaudible response] In the ganglia -- not exactly --
I guess we do have cells that protect -- that provide that protective environment,
but we have -- just like we had that blood barrier where we were able
to control what substances go to the cells, we also have a blood barrier in the testes
and it's produced by these sustentacular cells.
So let's put here that they have -- do you remember the name of the proteins between cells
that keep the cells from -- that seal the cells?
There's two proteins.
There's ones that keep the cells from separating.
Those are called?
[inaudible response] Desmosomes and there are proteins between cells
that seal the space between the cells.
[inaudible response] Tight junctions.
So these cells have tight junctions that form a type of blood barrier.
And the reason we want to have this, you know, type of blood barrier is
that it reduces the sperm cells from being exposed to toxins.
And it also prevents the white blood cells from attacking the sperm cells.
And the reason that the white blood cells want to attack the sperm cells is
because the sperm cells have a different number of chromosomes from all the other cells
of your body so the body cells consider them as foreign cells.
So you have to have a barrier there
so that those white blood cells can't go in and attack those sperm cells.
You probably remember from studying for your human anatomy assessment test, right,
that sperm cells and egg cells have half the number of chromosomes as compared to all
of the other cells in our bodies.
So these tight junctions between the sustentacular cells helps
to protect them from threat of attack.
So those are the testes.
Now our second organ in the external genitalia of a male is what we call the scrotum,
and if we want to say it plural, we say scrota.
Scrota is plural, two scrota and one scrotum.
And in terms of their structure we describe this scrotum as a sac that covers the testes.
It houses the testes outside the male body.
And the reason that we house the testes outside the male body is
because the testes need a little bit lower temperature than the rest of the human body
in order for the sperm cells to develop normally.
So let's put here that testes need a lower temperature than body temperature
for the sperm cells to develop normally.
If it's too warm -- if it has the same temperature as the body if it's too warm,
those sperm cells will not develop properly.
And so it is this scrotum, this sac of skin and muscles is basically what it is,
that is going to allow the testes to move at different levels,
to be placed at different levels based on, you know,
the ambient temperature, the temperature around.
So, you know, as I said these are necessary for the sperm to develop normally.
That's why for a while there used to be that talk
about what type of underwear should men wear.
Should they wear the boxers shorts or the, you know,
whitie tighties or whatever they call them.
And that's because the whitie tighties or the tight ones
with the bands keep the testes a little bit closer to the body.
They don't allow them to roam where the scrotum and the two, the skin and the muscles that make
up the scrotum to drop and, you know, raise them as needed to maintain
that little bit lower body temperature.
It's thought if you wear the boxer shorts that, you know,
that allows a little bit better adjustment of the testes.
So let's put here that the sac is made of skin on the outside just
like we've studied the integumentary system, all of our layers and also two involuntary muscles.
And these two involuntary muscles are called the dartos muscle
and the dartos muscle is the muscle
that gives the scrotum a wrinkled look, the wrinkled look that it has.