Now that we have a good understanding of the internal and external structures of the female
reproductive system let's talk about the female reproductive cycle and before we get into the
specific phases of the cycle let's talk about the hormones in which glands are really going
to be secreting and mediating this cycle so in terms of the hormones these are going to be
secreted by three main areas you're gonna have the hypothalamus and we'll discuss the hypothalamus
in considerable more detail when discussing the endocrine system we're also going to have
the anterior pituitary and then as you would think the female gonad or the female sex gland
is going to play a big role which of course we know now are the ovaries so let's break down the
terminology in terms of the female reproductive cycle a lot of times when people refer to this
cycle they think of it as the menstrual cycle or menstruation that's kind of a simplification it's
a bit more complex than that oftentimes we forget about the role in terms of what the ovaries are
doing so really when you think of what's going on in the ovaries as well as what's going on with the
uterus you put those together and then you get the four phases of the female reproductive cycle
now remember recall when we're talking about the uterine cycle we're really talking about what's
changing in that deepest layer of the uterus your endometrium so you remember the deepest layer
portions of that layer can actually slough off during menstruation so we're gonna break this down
into four phases the first is going to be what we refer to as the menstrual or menstrual phase this
is approximately five days and the first day of menstruation or menstrual flow is often referred
to as the first day of a new reproductive cycle so when you're counting down in terms of trying
to determine how far along a fetus is you think back in terms of your first day of a new cycle or
menstruation now in terms of what's going on with the ovary you're going to have the formation of
new oocytes in that region and it's going to start the process of maturation but in terms of
what's going on in the uterus you're going to have the flow of menstrual fluid and menstrual fluid is
made up of numerous things we typically think of blood but it's also going to have composition in
terms of mucous epithelial cells basically that stratum functionalis is going to sloth off in
this region here and it's going to follow the exit pattern of the uterine cavity the cervical
canal so the cervix the vaginal orifice and eventually through the exterior now all
this going to be left within the uterus for the endometrium is going to be that stratum basale
so five days is the typical length of the menstrual phrase then move into the pre-ovulatory
phase this is going to be the most variable in terms of length so if you have differences
in terms of how long the reproductive cycle is it's typically due to the length of this phase
now before we one thing that I forgot to mention at the beginning when we're talking about this
reproductive cycle we typically think of it as 28 days but this can vary considerably you can
have anywhere from 24 up to 30 to 35 in terms of the entirety of the reproductive cycle and
so if you have variation like this it's mostly due to this particular phase now what's going
on in terms of the ovaries is you're going to have a dominant follicle that's going to
to change and morph eventually into what we refer to as a mature follicle follicle so getting ready
for that oocyte to actually be expelled from the ovary into the peritoneal cavity now what's
going on in terms of the uterus is you're going to have the rebuilding of a new stratum functionalis
so remember its previously it was sloughed off in terms of the menstrual phase so you have to form
a new stratum functionalis within the uterus the third phase is going to be ovulation now
this typically occurs around day 14 it doesn't last more than a few days one to two days and
we refer to as an individual within this phase as ovulating and what occurs here in terms of
the ovaries is you're having the rupturing of that mature follicle and that is going to
release that oocyte or that secondary oocytes into the peritoneal cavity so remember in terms
of the ovaries this is intraperitoneal so if there's release it has to go into that
peritoneal cavity now we discussed it will not stay in the peritoneal cavity very long
before it moves into the Fallopian tubes or those uterine tubes in order to either
be fertilized or to eventually fertilize it or not it will end up in terms of the uterus the
fourth phase of the reproductive cycle is going to be the post ovulatory phase so the secondary
oocytes has already been ovulated it's moved into the peritoneal cavity into this uterine tube
and what occurs within this phase even though it's very consistently timed around 14
days is very dependent on whether the oocytes has been fertilized or not so recall in our
previous discussion of the uterine tube that fertilization often occurs in the ampulla and
either way it will move into the uterus now if it has been fertilized it will embed in the uterus
if it has not been fertilized then that's going to start that stratum functionalis to
begin the process of breaking down the cells in that region will start to die and then you will
move into that first phase or the menstrual phase to do the reproductive cycle again so
this review of the reproductive reproductive cycle really is going to wrap up our discussion
the female reproductive organs we're going to move into the male reproductive organs and as
we do that we will consistently talk about some of the homologues between males and females