start off first with looking at the uterine
tube. Just to remind you of the structures
associated with the female reproductive system,
cast your eyes on this diagram here.
Try to focus on, first of all, the orientation.
At the base of the diagram is the bladder, the
large round yellow structure in this diagram.
And on the right-hand side of the bladder,
or I should say on the posterior part of the
bladder, is the vagina. And you can see the vagina
is continuous with the cervix, and then the
uterus, a large pear-shaped organ. And then
you can see the lumen, colored in bright red
of the vagina and the cervix and also the
uterus, being continuous with the lumen of
the uterine tube, which is going to be the
topic of our first organ in this lecture. That
uterine tube lies very close to the ovary.
The ovary is colored in blue here. Now, the
anterior portion of the body is on the left-hand
side. The posterior part of the body is on
the right hand side. And not shown in this
slide, but right next to the vaginal passage will
be the rectum. So make sure you can orientate
yourself and make sure you’re now aware
of the location and continuity of each of
the organs that we’re going to discuss in
this lecture. The uterine tube is shown here
on the diagram. It’s between 10, 12 centimeters
long. Focus on the diagram, and then I will
talk more about the histological structures of
the uterine tube on the histological sections
also contained on this slide. The uterine
tube is divided into four different components.
They’re named there, the infundibulum, which
is the end part of the uterine tube, which
has these very numerous branches of mucosa
called fimbria. The fimbriae are actually
extensions of the mucosa, and they become
almost like erectile tissue at the time of
ovulation. And they are going to actually
wrap around the ovary, or very close to the
ovary, to optimize the chance that the ovulated
oocyte will pass into the uterine tube.
The next part of the uterine tube is the ampulla.
This is by far the longest part of the uterine
tube, and it is the site where fertilization
occurs. And then there’s a very small portion,
the isthmus, which is very close to the entry
into the uterus, and then a small interuterine
component or segment also labelled. So make
sure you now understand that there are these
four components to the uterine tube. And before
we go any further, let us just recall that
at ovulation when the oocyte is released, it
is still yet to complete its second meiotic
division. It has been sitting in the ovary
possibly for 50 years because, as you may
know, these oocytes develop from oogonia prior
to fetal life. And although there is a lot
of atresia, at the time of birth, you may
have only 400,000 to 500,000 of these oogonia
remaining in the ovary. And they sit there for a
very very long time during the reproductive
life of the female, which can last until the
age of about 47 to 55. So really, one of these
oocytes that is ovulated may be 50 years old.
And because of that, and because it’s arrested
in the second meiotic division, during that
long time, there is a possibility of errors
in the meiotic division process. And this can
give rise to anomalies, such as nondisjunction
arising, for instance, in the trisomy of chromosome
21 or Down syndrome. So, it’s important
to understand that there is this long arresting
of the oocyte in the second meiotic division.
And it’s only after fertilization that meiosis
is then completed. Well, what happens now
is that the oocyte enters into the uterine
tube. And on this slide, you can now see there
are three sections through the uterine tube.
The top left section is the uterine tube cut
in very low magnification. And you can see
various components in a high magnification.
The uterine tube has a very thick muscular
wall. That muscular wall or the muscularis
creates peristaltic contractile activity that
can move fluid and content such as sperm from
the uterine end of the uterine tube up towards
the ampulla where fertilization may occur.
So it enhances movement of the sperm up to
that region. Conversely, the peristaltic wave
of this muscle can work in the opposite direction
after fertilization and enhance the transport
of the fertilized egg towards the uterus for
implantation. At the high magnification, you
can see details of the mucosa. The mucosa
is a very folded epithelial surface.
Remember the term mucosa refers to an epithelial
surface, and it’s supporting lamina propria in a
tube that is exterior to the body, that opens
exterior to the body. And if you think about
the anatomy of the reproductive system I described
earlier, this tube does eventually lead to
the outside of the body. The epithelium has
two sorts of cells. It has a ciliated cell.
You can see the cilia here. And a little dark
pink line running along the surface of these
cells are the basal bodies in which these
cilia are attached, and they all beat together
to move fluid along, and to move the oocyte
along, and also the sperm along so they meet
each other for fertilization. Besides being
an organ for transport and providing a location
for fertilization, it’s also a very important
tissue for making sure there is nutrition
inside the lumen for the oocyte, the sperm,
and also for the possibility of the fertilized
egg. And they are called secretory cells or peg
cells. Now, before we move on to looking at
the uterus, the uterine tube also undergoes
changes during the cycle. At around the time
of ovulation, these ciliated cells, and the
peg cells are maximum in number, and they
can be as much as 30 microns in height. And
during periods of nonovulatory phases of the
ovarian cycle, such as the follicular phase
and the luteal phase, these various cells
can be reduced to half their height and they
can lose the cilia and become non-secretory.
It’s only after the influence of estrogen and
progesterone that they reach their optimal
state of activity at the time of ovulation.
Estrogens actually create ciliogenesis in
the ciliated cells, so they acquire cilia
and more cilia at the time of ovulation.
And progesterone stimulates the secretion of the
peg cells to produce the nutritious fluid
that we spoke about earlier. I want to move
on now to discuss the uterus. And again on this