00:00
Now, we’re up
towards the epididymis. On the right-hand
side, you can see a section taken through
the testis and the epididymis. Testis is shown
here on the label, and then the epididymis
is shown on the far right label. In between
are the efferent ducts. Have a look at this
histological section, including the testis,
the efferent ducts, and the ductus epididymis.
00:33
And now, have a look at the figure. And just in
your own mind, draw a line where you think
the section passed when the histologist sliced
the section through the testis, the efferent
duct, and the epididymis to obtain the section
that you’re looking at here. It is important
sometimes in histology to be able to work out
the orientation of how sections were actually
taken through an organ. That’s just
a little exercise for you to do partly
of interest. Well, we now are looking at the
epididymis. Have a look at the two sections
shown here. Even though they are taken at
two different magnifications, there are a
few features I wish to point at. First of all,
the bulk of the cells are called principal cells.
01:33
They exhibit stereocilia, long extended
branching microvillus-like processes from
the apex of their cells. They’re important
to be able to absorb an enormous amount of
fluid from the contents, from the lumen of
the epididymis. Because the epididymis, one
function is to absorb all the fluid that moves
from the testis up into the epididymis duct,
the fluid that’s added by secretions from
the seminiferous tubule and by a secretion
from the cells in the ducts I’ve already
dealt with leading to the epididymis.
02:19
These stereocilia are then very important for that
absorptive role. In the center of the lumen
of each section through the epididymis shown
here, you can see spermatozoa, many, many,
many spermatozoa. The testis produces 300
million spermatozoa per day. Very different
to the ovary, whereby, only one oocyte is
ovulated every month. Huge contrast.
02:59
When you look at the epididymis, you can see smooth
muscle around the wall, just underneath the
lamina propria supporting the epithelium.
On the left-hand side, you don’t see a lot
of smooth muscles. On the right-hand side
where the smooth muscle is labeled, you do.
03:19
And that’s because, on the left-hand section,
you’re looking at a section through
the epididymis taken towards the head of the
epididymis, where really the prime role of
the epididymis here is absorption. And therefore,
you see a lot of stereocilia, as I’ve pointed
out, on the apex of many other principal cells.
Whereas, the section on the right contains
a lot of smooth muscles. And that smooth muscle
is important because, during ejaculation,
that muscle is going to contract and force
those spermatozoa along into the vas deferens
which also contracts to expel the spermatozoa
out through the penis during ejaculation.
04:09
So that muscle is very important and there
are lots of layers of muscle there. The other
thing you can’t notice really on this section,
but I’ll tell you about it anyway, is that
on the left-hand side, the epithelial cells
that are doing all the absorption, they are
very busy cells. They are tall. They are about
30 to 40 microns in height. Whereas, the ones
on the right-hand side where the prime role
is merely to move the spermatozoa into the
vas deferens during ejaculation, these epithelial
cells are half that size, half that height,
and they don’t exhibit as many stereocilia
on their surfaces.