all right ninja nerds In this video we're going to talk about the female reproductive cycle Now in this video we're going to talk about the ovulatory cycle and we're going to discuss the menstrual cycle and see how these two cycles are interconnected and intertwined because that's really the crucial point Not just looking at one cycle and all it does but looking at how these two cycles are really really intertwined together Okay but before we do that let's go ahead and start where this whole pathway begins Everything upon which these cycles are working are dependent upon the hormones produced by the hypothalamus Okay so let's start up here in the hypothalamus So here's your hypothalamus And in the hypothalamus you have two different special nuclei that are secretreting specific types of hormones So for example let's say that this red one over here this red group of nuclei we're going to call these guys we're going to call them the pre optic nucleus And then these orange ones over here we're going to specifically call these guys we're going to call these ones the arcuate nucleus Okay so we got the arcuate nucleus which is the orange ones and then we got the preoptic nucleus which is these red ones What these guys are doing is they're secretreting a very important hormone That hormone is called look at this what they secrete they secrete what's called gonadotropen releasing hormone What gonadotropen releasing hormone does is it comes down here into the anterior pituitary and in the anterior pituitary there's these cells called gonadotropes And these gonadotropes once they're stimulated by gonadotropen releasing hormone they secrete two chemicals into the bloodstream Look at these two chemicals that they're releasing This one is called FSH and this one is called LH FSH stands for follical stimulating hormone and LH stands for luteinizing hormone And they're going to come down here and they're going to work in the ovary But before I show what they're doing in the ovary we need to discuss something real quick All right So whenever a female is born so at birth she has these special types of stem cells And these stem cells are called ooniums Okay so an oonium Now an oonium is a stem cell It's a diploid stem cells What does it mean when it's diploid it means it's 2 N right 46 chromosomes 23 of them maternal 23 paternal What happens is once the female is is actually born her oagoniums she'll have all the oagoniums her stem cells that she'll ever need What happens is while the child is growing up before puberty these ooniums are getting converted into this follicle right here You see this follicle right here this follicle right there is actually specifically called a primordial follicle So what is this one right here called it's called a primordial follicle And again when is this occurring when are you shifting from an oagonium which is a dloid into a primordial follicle when is this happening which is still by the way this one right here is still diploid So this primordial follicle is still diploid But when is this occurring this is occurring during the childhood pre-puberty So this is occurring pre- puberty So when is this occurring again guys pre puberty But then what happens is when the female reaches puberty and she starts undergoing these specific ovulatory cycles So now she's hit puberty and she has her primordial follicles By the time she hits puberty she has tons and tons of primordial follicles But then look what happens once she hits puberty There's specific local chemicals Local chemicals So what kind of local chemicals like local androgens So again what type of chemicals here like specific types of localized androgens These localized androgens not FSH not LH these localized androgens are stimulating some of these primordial follicles at puberty to start shifting and turning into this next follicle right here Okay so let me repeat this one more time When you're born you have all the ooniums you'll ever need which is a diploid stem cell During that pre-puberty pre-puberty time period what happens is your oegoniums get converted into primordial follicles which is still 2 in meaning it's diploid Then what happens is it's going to get stimulated by the time we hit puberty all the way until you reach menopause right there's going to be localized androgens that are going to stimulate the conversion of some of the primordial follicles into what is this one right here this one right here is called a primary follicle So this one right here is called a primary follicle Okay so we got pre-puberty all the way to this guy which is the primordial primordial to a primary follicle One more thing I told you that this is diploid right it's actually frozen in a specific step of what's called meiosis It's actually frozen specifically in prophase one So again this primordial follicle it's diploid but what happens is it's getting ready to start undergoing meiosis one but it's frozen in prophase one Okay now we're at the primary follicle What happens is you see this FSH right here This FSH is super critical for this step right here going from this primary to this next one here Let's actually label all of these So for example this is a primary follicle How would you describe a primary follicle it's a primary oasite Primary oasite which means it hasn't undergone meiosis one still frozen in prophase 1 with a single layer around it of cubuidal or columnar like follicle cells So again a primary follicle is a primary oasite meaning it hasn't undergone meiosis one and or finished meiosis one and around it has a single layer of cubuidal or columnar like epithelial cells that's a primary Then after that look what happens it starts proliferating and makes multiple types of these granulosa cells Now this cuboid or columnar this one right here is called a early secondary follicle Let's explain something here before we go into each one of these This primary follicle it gets converted into this early secondary follicle How FSH look what FSH does FSH stimulates this step right here Look what he does FSH comes right here and he stimulates this step of converting a primary follicle to early secondary follicle So what's actually happening in this step look what happens to the cuboidal cells They went under we'll go underwent proliferation So we went from just a single layer to multiple layers That's one effect of FSH is multiple layers of granulosa cells What else happened fsh also stimulates this oasite to produce this pink glyoprotein membrane around that What is that pink glycoprotein membrane around it called it's called the zona palucida Okay so FSH is stimulating the proliferation of these follicle cells to multiple layers It's also stimulating this actual oasite to produce a glyoprotein layer called the zona palucida And look what else it's causing the production of Look what else is coming out of this So these cells right here when they're stimulated by the by this FSH look what they're producing they're producing estrogen Okay so let's go ahead and recap this one more time What's this FSH doing to the primary follicle it's stimulating these primary follicles to undergo replication make multiple layers stimulates it to to produce a glyoprotein membrane around it called the zona palucida and it also causes the production of estrogen Okay what about LH is LH involved in this step yes he is You see these like uh maroon violet like uh uh cells around it those are called theal cells Theal cells Let me show you what theal cells are actually doing These theal cells are pretty cool Look at these theal cells Let's say we zoom in on a theal cell here Here's our theal cell And what happens is the granulosis cells are right next to this theal cell So if we have a granulosis cell right adjacent to it look what's happening here This is the beauty of it LH is acting on this cell So it's acting on this cell And what's happening in the STL cells it's taking cholesterol and converting it into androigens But who's stimulating this LH lh is actually stimulating the conversion of cholesterol into androgens like androstine dione But then look at what's right next to this theal cell What's right next to them these green cells these granulosa cells Look what happens to these androgens They move right into this cell and they eventually get converted into estrogen But who's stimulating this mechanism this is the job of FSH So FSH is actually stimulating what he's stimulating the conversion of these androgens that came from the theal cells into the granulosa cells and he converts it into estrogen That's beautiful So FSH is stimulating the production of estrogen But how you need the presence of luteinizing hormone So luteinizing hormone is actually going to be there How because it's going to stimulate these theal cells and tell these theal cells to produce androgens And then those androgens will go into the granulosis cell and FSH will stimulate specific enzymes like aromatase enzymes that convert it into estrogen So it's really important in this step here Okay very very nice So now let's go to the next one Early secondary follicle FSH and LH are also stimulating this step too So in the same way who else is going to be stimulating this step right here you're still going to have FSH stimulating this step And who's going to be stimulating the theal cells in this step you're still going to have luteinizing hormone stimulating the conversion of the early secondary to this next one Look what else it does So not only does it cause the actual proliferation again of the actual cell layers but look what else it does It starts telling these uh granulosis cells to start producing follicular fluid What is follicular fluid follicular fluid is actually primarily consisting of what's called hyaluronic acid So it's not only causing again the proliferation of these granulosis cells it's not only causing the production of estrogen it's not only causing them to proliferate even more but it's also causing them to produce follicular fluid which is rich in hyaluronic acid So now we produce these pockets of follicular fluid Who's responsible for producing these pockets of follicular fluid fsh So FSH is doing what he's causing multiple layers of granulosis cells to be made Right so in this step what's happening to these granulosis cells you're making more What else is happening they're producing pockets of follicular fluid which is rich in hyaluronic acid What else would be happening same thing that happened in this step the production of estrogen So you're also going to be producing in this step you're going to be producing estrogen So now that we know how this estrogen is being produced with the theal cells the LH is stimulating the theal cells to convert cholesterol to androgens Then FSH is taking those androgens that move into the granulosa cells and stimulating their conversion into estrogen We don't need this anymore So now we know this Okay So again what is FSH doing to this early secondary follicle as it converts into this next one it's causing proliferation pockets of follicular fluid and the production of estrogen Oh man so beautiful It should make so much sense guys Okay so primary to early secondary FSH and LH is stimulating early secondary into this next one where there's multiple layers pockets of follicular fluid and estrogen production This next one is actually called a late secondary follicle You can tell that because it has more layers in the early secondary and it has pockets of follicular fluid And to continue to keep going with this you know how I told you that the primordial follicle was again a primary oasite the primary follicle is a primary oasite The early secondary follicle is still a primary oasite and the late secondary follicle is still a primary oasite What does that mean it means it hasn't finished meiosis one Okay it's getting ready to though All right so now look what happens This late secondary follicle it's going to get more stimulation from who from FSH and LH So FSH is going to continue to stimulate what the proliferation of the cells the pockets of follicular fluid And what's the result of actually this you're still going to produce more estrogen Okay who else is stimulating this pathway too it's also going to be the presence of luteinizing hormone Luteinizing hormone is actually going to be stimulating the theal cells to produce androgens Androgens are going to be converted into estrogens by the granulosa cells with the presence of FSH Now look what happens here It's stimulating this late secondary follicle into this next one But you see how there was just these little pockets of follicular fluid FSH keeps stimulating these granulosis cells to produce more and more and more follicular fluid till eventually these two pockets they come together and they coalesce and make one big fluid fil cavity You see this one right there that's your fluid fil cavity This fluid fil cavity here which is going to be rich in follicular fluid and again that follicular fluid is hyaluronic acid This pocket big big huge lake of follicular fluid that is called the antrum So this big blue structure right here is now called the antrum And what is that antrum how is that antrum formed again FSH is stimulating these granulosis cells to produce those follicular fluid right rich in hyaluronic acid And eventually those pockets of follicular fluid get so big that eventually they come together They coalesce and make one big fluid fil cavity called the antrum Okay Next thing you see how this is a late secondary follicle This one is called a graphion or vicular or tertiary follicle But watch this You know how I've been telling you the whole time that again if we come back over here primordial follicle was what it was a primary oite Let's write that here It was a primary oasite What about a primary follicle it was a primary oite What about an early secondary follicle it was a primary oasite What about a late secondary follicle it was a primary oasite What about a graphian a graphian follicle is actually going to be a secondary oasite And be so it actually underwent meiosis one So what's meiosis let's actually show you what meiosis is up here So real quickly if I have a dloid stem cell right a parent stem cell and what happens is I undergo meiosis one As the result of meiosis one I make two hloid daughter cells Then those two hloid daughter cells they undergo meiosis 2 and produce two more hloid daughter cells for a total of four hloid daughter cells All right So when you're going from this dloid stem cell to these two hloid daughter cells this is called meiosis one Meiosis one All right So this is whenever you had that primordial follicle It's still undergoing my it hasn't completely finished meiosis one It gets converted into a primary follicle Primary follicle gets converted into an early secondary early secondary to a late secondary And then look look what happens to his late secondary As a result he under goes meiosis one and produces a hloid daughter cell and then another hoid daughter cell This right here one of them actually becomes what's called a polar body and he under goes degradation and then he before after he'll actually can undergo meiosis 2 and produce polar bodies like a third and fourth These will undergo degradation also This one right here is your secondary oasite So this one right here is called your secondary oasite and eventually he'll go undergo meiosis too but he doesn't finish it He gets stuck in metaphase 2 So this graphian follicle is a secondary oasite frozen in metaphase 2 Okay So we're at that point right now What was this second step here this second step when you're going from these two hloids to four hloids is called meiosis 2 All right So we're at that point now Okay So the graphine follicle it's a secondary oasite So going from this late secondary to this graphine I underwent meiosis one and produced a secondary oasite in metaphase 2 I also produced estrogen I formed this lake of follicular fluid and I still have my zona palucida and I have all these granulosa cells Oh real quick if I were to kind of highlight it you see these cells these group of cells I'm going to kind of highlight it in blue here going all the way around them These cells right here that are just directly wrapping around this secondary oasite frozen in metaphase 2 these green cells those green cells right there are called corona radiata cells Okay so they're just the actual group of cells that are directly wrapping around that secondary oasite Now we need to talk about something real quick Okay what is this whole phase here called this whole phase of when I'm going from a prime uh from technically a primordial to a primary a primary to an early secondary an early secondary to a late secondary and then a late secondary to a a tertiary or graphion follicle This is called the follicular phase So again what is this here called this is called the follicular phase And again in the follicular phase what am I actually doing and I'm going from a primordial follicle to a primary follicle to a early secondary follicle to a late secondary follicle to a graphian follicle Okay that's what's happening So in this step let's actually do it again What happens here primordial all the way to a graphian follicle Okay And who is stimulating this step primarily primarily it is FSH But who else is producing produced in a small amount that helps in this process it's also going to be luteinizing hormone What's the product of this reaction here this follicular phase Do you remember that you actually undergo mitosis or proliferation So there's mitosis not meiosis mitosis of these granulosis cells making multiple layers What else there's estrogen production So estrogen is produced What else is happening you're producing follicular fluid And what else at the end of this follicular phase you go from a primary oasite all the way to a secondary oasite Okay Now we need to talk about something else too This follicular phase is occurring from about days 1 to 14 So again it's occurring from about days one all the way to day 14 This is on average Not every ovulation cycle is obviously perfect But on average a follicular phase is generally days 1 to 14 So around the midpart of the follicular phase so days 7 8 or nine right estrogen levels start rising because you're producing a lot of estrogen during this time period So you know where estrogen is actually going it's going into the bloodstream So look it's going into the blood It's moving into the blood here You're producing it here It's moving into the blood right there Right now this estrogen let's follow it Look what happens here It's actually going to come through the blood and look what happens to this estrogen levels So as they're rising around midfollicular phase they come over to the hypothalamus and they also go to the anterior pituitary and look what they do to it They exert a negative feedback mechanism Okay so as estrogen levels are rising right because it was in the blood And as it rises in the blood what happens it comes up to the hypothalamus and inhibits the hypothalamus from secretreting G&R It also inhibits the anterior pituitary from releasing FSH and LH Now when it does that you're not going to make as much FSH and you're not going to make as much LH And then what's going to happen this actual production of estrogen is eventually going to drop But estrogen levels drop but they come back again So now let's actually say that estrogen levels come back up again So estrogen levels they get they actually increase Now when do they increase again to high high levels around day 14 So let's say that we get to about day 13 day 14 estrogen levels start rising in the blood again So now let's come back over here Let's show the second time here as red So when is this time this is around the end of follicular phase and this is when midfollicular phase and then what happens when that happens exerts a negative feedback mechanism Look what happens when it rises again towards the end of the follicular phase does something really really weird Oh look at that Isn't that weird guys it stimulates the hypothalamus to produce tons of G&R It stimulates the anterior pituitary to produce tons of LH Now you notice I didn't say a lot of FSH Why because you know the graphine follicle is also really special Whenever you get to like the end of the follicular phase it notices this rise in estrogen and it produces a really cool chemical Look at this chemical that this guy produces This chemical is called inhib Now technically if we were to be specific it's inhib Look what inhib does It comes over here and it inhibits the anterior pituitary from releasing FSH Let me repeat that one more time The graphian follicle as a result of this high amounts of estrogen production high amounts of FSH production it releases inhib Inhib B then inhibits the anterior pituitary from releasing FSH But what was the high estrogen levels towards the end of the follicular phase doing the high estrogen levels at the end of the follicular phase were promoting a positive feedback mechanism to stimulate the hypothalamus to release g& RH and to stimulate the actual anterior pituitary to produce tons of LH You know what this is called whenever you produce massive amounts of LH it's called the LH surge Okay Now look what this LH is going to do This LH is actually going to come over here to the graphan follicle and it's going to work in this step primarily So he is primarily going to be working in this step this this whole graphian follicle Look what he does It's actually really cool So you know what he does over here You know there's blood vessels that are supplying this So let's say I draw like a tiny system of blood vessels right here What LH does is is it increases the actual blood flow and permeability to this part of the graphine follicle If it applies a lot of vascular permeability to this part of the follicle what happens you start producing a lot of follicular fluid So this follicular fluid production continues to increase But over here there's not a lot of follicular fluid being produced Guess what else he does over here he activates special enzymes Look at these enzymes Look at what these enzymes are Little scissor enzymes You know what these scissor enzymes are they're called proteasis You know what these proteases are going to start doing they're going to start eating away around this tissue of the graphine follicle So it starts eating away and breaking down specific tissue around the graphian follicle So what does this actual oasite look in a different view look I'll show you here in a different view So let's say here's the oasite and then look it's coming up off the surface right there So right here is the oasite It's popping up off the surface and then what's surrounding it that's zona palucida right so there's that zone of palucida surrounding it right here Then right around that you're going to have those granulosis cells right so all those granulosa cells are surrounding it Now it's popped up across the top of the surface here What luteinizing hormone does is he activates specific enzymes these proteolytic enzymes and these proteolytic enzymes start cutting up that little tissue around that area that's keeping it elevated above the surface and it's increasing the blood flow to the antrum over here What eventually happens if you start cutting this little structure away that stigma they call it It pops it out It pops the secondary oasite out of this graphine follicle So what would that what will happen then look what happens Look what comes out of this Out of this we have our secondary oasite who's frozen in what he's frozen in metaphase 2 He has the zona palucida membrane around him And then directly around that what do you have you have those granulosa cells Specifically which ones the corona radiata cells What is this step right here called whenever you eject or you pop that secondary oasite that's frozen in metaphase 2 out of the graphine follicle this right here is called ovulation when does that usually occur usually this event occurs around midcycle but like I said it's not everyone has a perfect cycle but it's usually around day 14 or day 15 that's what we assume right so again this is actually going to be called the ovulatory phase okay now the ovulatory phase like I said is technically assuming a normal cycle about days 14 to 15 anywhere within this time period Okay So somewhere in between day 14 and 15 is when the ovulatory phase is occurring And again who's triggering this phase this phase is triggered by the LH surge Okay that's the ovulatory phase Now look what else really happens This is really cool Females are just intuitive that they know that they need to be able to take this oasite into their fallopian tubes You know what happens right around this time whenever the ovulation occurs this fimbra you see these little fingers here of the fallopian tubes they become really stiff and then they start scraping across the surface of the ovary And when they scrape across the surface of the ovary it creates like little fluid fil currents So there's like some gnarly waves in here that are being produced right and it's kind of kind of like pushing and scooting that little OSI towards this actual frame of the fallopian tubes So look what happens as a result It starts moving this guy towards the fallopian tubes and it catches it So what happens is it catches the actual secondary oasite frozen in metaphase 2 catches it Once it's caught it under goes this little beating mechanism So look what happens in here In here we have these simple columnar cells and these simple columnar cells on their surface they have psyia and the psyia are going to beat that little oasite into this area of the actual fallopian tube So you see this area right here this is called the ampula of the fallopian tubes Okay so it pushes it right into this area and keeps it localized in this area for fertilization to eventually occur Right so whenever the sperm cell comes to that vicinity Okay So ovulation it ejects the secondary oite out the frame becomes stiff and push fluid fil currents that push it into the femre and it catches it and it keeps it in the ampula until the sperm cell comes and actually tries to fertilize it Okay Now what else happens okay So we did the ovulatory phase Now we're going to go into this last phase So this last phase here is actually called specifically it's called the ludal phase And you'll see why So it's called the lutil phase Okay So where were we at we were here at the graphion follicle where it ejected that secondary oasite frozen in metaphase 2 out What happens is LH is what stimulated that process But guess what else it stimulates this The structure here becomes filled with blood and it's called the corpus hemorrhagicum When it gets filled with blood LH actually does something again So let's actually represent LH in this color Now so LH is actually going to stimulate this step again So not only is he going to trigger ovulation but he's going to turn some of these cells these granulosis cells the ones that are still there he's going to specialize them He's going to differentiate them They're going to start accumulating a lot of lipids a lot of cholesterol a lot of fat and it's going to turn yellow You know what the another word for yellow is is ludia You know so what happens this structure here the graphine follicle luteinizing hormone stimulates him to get converted into this specialized hormone producing factory You know what this hormone producing factory is called this hormone producing factory is specifically called the corpus ludium So what is this structure right here called it's called the corpus lutium Now LH triggers the conversion of the graphine follicle that ruptured into the corpus ludium But you know what else he does so look what happens Corpus ludium you know see you see see this LH he's going to directly stimulate the corpus ludium And as a result the corpus ludium produces a very very important hormone This hormone is called progesterone Okay So this hormone is called progesterone So LH is stimulating the corpus ludium to not only be converted from a graphian follicle that ruptured into this corpus ludium but it also stimulates the corpus ludium to produce progesterone Now this ludal phase that I told you right so again what's the trigger here this is going to be converting the what graphion into the corpus ludium Who's the primary hormone involved in this step the primary hormone involved in this is going to be luteinizing hormone And then what's the result of this luteinizing hormone luteinizing hormone is actually stimulating the corpus ludium to produce what progesterone So it's stimulating the corpus ludium to produce a very important hormone which is called progesterone That's what ludinizing hormone is doing Now the ludial phase is about from now again assuming a normal period I'm sorry a normal ovulatory cycle is from about days 15 to 28 So again on normal the ludial phase is generally approximately about days 15 to 28 All right And the ludial phase is going to be what happens when the graphian follicle that rupture gets converted into the corpus ludium And then the luteinizing hormone stimulates the corpus ludium to produce progesterone Now that will pretty much give us everything that we need to know for the ovulatory cycle Okay In the next video we're going to go over the menstrual cycle and see how estrogen and progesterone hormones are going to affect the actual uterus and all the different types of activities that occur There