hi everyone Dr Mike here in this video we're taking a look at an overview of the female reproductive cycle we're going to take a look at what's happening at the ovary what's happening at the uterus what's happening in regards to all the various hormones that are being released and a lot more let's take a look now to begin we need to understand that the female reproductive cycle is actually two major Cycles it's what's happening inside the OV so the ovarian cycle but also what's happening at the uterus so the endometrial cycle both of these two things are super important so we're going to take a look at the ovarian and uterine cycle and the various changes that occur associated with each and we're going to have a look at the various hormones associated with these changes as well now to begin we need to understand that the ovarian and uterine Cycles or the femal reproductive cycle goes from 0 days to 28 days now this is an approximate it can be lower it can be higher but only by a little bit it could probably be as low as 25 days and as high as 34 is days but it's variable the average is 0 to 28 so we're taking a look at the 0 to 28 female reproductive cycle first of which is the ovarian cycle so remember that there are many things happening in the ovaries what's happening is that this is where our uyes are our egg cells now this is where the genetic material resides and this genetic material needs to replicate it needs to undergo two phases of meiosis but it also needs to be nourished and protected and so this is what's happening in the ovarian cycle is follicular Genesis which is the development of the follicles that protect the egg but then also what happens after the egg is ovulated we're going to have a look at the endometrial cycle as well so this is what's happening at the uterus to prepare it for implantation and the hormones ovarian cycle to begin with there are two major phases associated with the ovarian cycle the first phase is that of what we call the folicular phase the follicular phase the second phase is what we call the luteal phase the luteal phase now as you can see because we've broken it up in accordance with days here that from 0 to 14 we have the folicular phase and then from day 14 to 28 we have the luteal phase let's take a look at this to begin with because the follicular phase is associated with taking the uite or the egg for example so here's the uite or egg in a primordial form now that primordial uite will turn into a primary uite and this primary uite and I'm not going to write that up yet this primary oite is surrounded by a thin layer of cells and this thin layer of cells we call pregranulosa cells pregranulosa cells and the whole thing with the pregranulosa cells and the uite and this is called a primary uite this is called a primordial follicle primordial follicle now this primordial follicle will start to mature and develop and over time what's going to happen throughout this follicular phase so going from day Zer to day 14 is this primordial follicle will get that oite and those pregranulosa cells will turn into granulosa cells more cuboidal shaped cells and the uite will be surrounded by this thing called a Zona paluca which helps prot protect it and is very important when it comes to fertilization once the sperm gets into that zone of paluca it's like the screen doors of the house all shut and don't let any more sperm in so now we've got these granulosa granulosa cells and we've got the zon of paluca as well zon of paluca and this is what we call a primary follicle so it goes from a primordial follicle to a primary follicle now this whole time it's still a primary uite so don't get that confused even though the follicle name changes it goes from a primary follicle into a secondary follicle and the secondary follicle is very similar still has the zone of paluca except there's one major change well a couple first of which is you can have a couple of layers of granulosa cells so I'm just going to draw it up like this and you're going to have some additional cells called ther cells so you have these ther cells now on the outside here so these are ther cells and you still have your granulosa cells and you still have your zone of paluca granua cells this now is called a secondary follicle secondary follicle and this secondary follicle will turn into now I haven't told you about what they do I will I promise I'm just going through the phases the secondary follicle will turn into a mature ultimately a mature follicle now what this mature follicle does by day 14 is it ovulates now what that means is that you have these granular cells like this you have these F cells that have now developed even further right on the outside and the uite has ovulated and it takes some cells with it because it still needs to be nourished right now that's an important point because I haven't told you what any of these cells do as it goes from Day Z to day 14 the development of this follicle these follicles which we call the follicular phase from a primordial follicle to a primary follicle to a secondary follicle to what we call a mature or graffian so let's call this an anol or let's call it a graphion or you could even call it a mature follicle right this is the one that ovulates now the granulosa cells and the Thea cells are super important what the granulosa and ther cells do is they ultimately produce estrogen now specifically one type of estrogen that's most important here is called estral now here's the thing this whole process going from here to around about here is independent of any hormones it really doesn't need hormones to do this right now if we have a look down and look at the hormones what's happening during this process let's first focus on luteinizing hormone and follicle stimulating hormone now remember these hormones these two here they're ultimately released from the hypothalmus right specifically they're released from the anterior pituitary gland so what happens is the hypothalmus the hypo thelus will release a hormone called gonadotropin releasing hormone and this goes down to the anterior aspect of the pituitary gland which then releases these hormones this happens at puberty right now let's have a look at what's happening at these hormones lutenizing hormone and follicle stimulating hormone they're not super high right let's start with ltin let's start with uh follicle stimulating hormone so what you'll find here is that follicle stimulating hormone at Day Zero is up here and it starts to drop down right let's do the same with lutenizing hormone right lutenizing hormone it's here and it starts to drop down slowly interesting now importantly what these two hormones do most specifically follicle stimulating hormone is by the time we hit this phase here we need follicle stimulating hormone to stimulate these secondary follicles to turn into more mature follicles to these anal follicles graphium follicles more mature follicles we need FSH for this if FSH isn't here at this step what ends up happening is these cells just all die off now every month right at Day Zero you have around about 10 to 30 of these these follicles undergoing this process and again without FSH they'll all just undergo a treesia and die so what you'll find is that because FSH is released it allows for that selection process now here's the other thing that's important as it selects and it's going to take from 10 to 30 it's only going to select one right one mature one to ovulate one single ovam as it does this and these granulosa and ther cells get bigger and bigger and bigger these granulosa and Thea cells produce estrogen so as the as the follicle develops the estrogen right estral specifically it starts low but it starts to go higher now can you see a pattern here right as the estrogen gets higher the FSH and LH gets lower this is important because the estrogen that's released from these Thea and granulosa cells goes back to the hypothalmus and says and provides negative feedback says stop releasing G outat trop and releasing hormone stop releasing luteinizing hormone and follicle stimulating hormone why would it want to do that it does that because it's now already selected its one mature follicle that it wants so there's no point continually releasing these hormones to keep this process happening we want it these to stop and just have that one selected one now the estrogen will continue to go up and inhibit the FSH and LH until something important happens right so again we're not at day 14 yet we're not at this point what we're going to find is as we get just maybe like 24 hours before day 14 the estrogen levels that are released by these ther and granulosis cells it's starts to just Spike right up now here's the interesting thing while relatively low levels of estrogen inhibit FSH and LH high levels of estrogen stimulate them we don't know why but it does and so when we have this higher level of estrogen and it stimulates FSH and LH what we end up getting is the FSH down here and the LH down here but once it starts to get right once these levels start to get high enough we get a surge now the surge in this case predominately is going to be that of lutenizing hormone we also get a surge of FSH but importantly we've got this big surge of LH and again this big surge of LH is happening just before day4 and what this big surge of LH does is FSH follicle stimulating hormone is really important in the follicular phase that makes sense right so FSH is really important in this phase here at day 14 where we have ovulation let's write that down I think that's important day 14 where we have ovulation occurring this is important because of LH LH is responsible for that ovulation beautiful so that's because of that Spike there now the thing is that once this happens we've got the ovulation occurring the egg has been taken up by the fim and is now in the uterine tube right the fallopian tube let's just have a look here right this remaining thing here if I were to draw it across we're now in the luteal phase right so we've now got this big empty looking body and this big empty looking body starts to produce a whole bunch of progesterone this is called the corpus luteum hence why it's called the luteal phase so this is called the Corpus Corpus means body right luteum luteal means yellow it looks yellow right because cholesterol we turn cholesterol into progesterone and we turn progesterone into androgens right like testosterone and we turn androgens into estrogen like estradiol all comes from cholesterol so what's happening in this corpus luteum phase that goes throughout this process here is it starts to produce huge amounts of progesterone so what we end up getting is low levels of progesterone through most of this process we have a little bit of a spike here but once we hit day 14 and this corpus luteum happens we get this big spike of progesterone right we get this big spike of progesterone what happens with all these other ones they start to drop off again so we got estrogen dropping off we've got follicle stimulating hormone dropping off and we've got oh sorry luteinizing hormone dropping off and we've got follicle stimulating hormone dropping off but here for this luteal phase we've got heaps of progesterone all right we haven't spoken at all about what's happening in the endometrium so far the endometrial lining or the endometrium or the uterus has three major phases the first phase is called menes and this is bleeding now as you can see menes goes to round about day five day five and then after bleeding after menes we've got the proliferative phase we've got the proliferative phase proliferative and then we've got the secretory phase now remember this this is what's happening at the endometrium the secretory phase so if we look at endometrial changes that occur so just so we've got enough room I'm going to drop these because I didn't do units it's okay I'm just looking at gross changes that happen so that's not a problem I didn't do any units on purpose and it's important to understand the unit changes here because some are measured in microliters uh micrograms per microl or mil some are measured in pics nanog so they're all you can't compare them in regards to their concentrations this is just general uh spikes for example and Peaks and troughs now the endometrium what happens menes menes is bleeding goes for about 5 days if we have a look at the thickness of the uterus it like this it's going to be thick and then it starts to bleed away and Slough off so if this whole thing was the what we call the functional layer of the uter of the endometrial lining we're focusing on the functional layer the functional layer is the layer that can implant the fertilized embryo but also can thicken become more vascularized and produce enzymes and uh various secretions like mucus during menes the uterine lining gets thinner and that's because bleeding is occurring it's sloughing off this sloughing off is happening because the hormone levels are really low that's important but as you can see in the proliferative phase it starts to get thicker again now it's getting thicker again because we're starting to get an increase in estrogen levels what estrogen does is it increases the thickness of the endometrium right so it starts to get thicker that's great as you can see as we move through and not just uh estrogen is being produced we now start getting progesterone progesterone reinforces this and says hey endometrium get thicker get more vascularized and by the so here we got the proliferative phase this is simply just saying get thicker get thicker get thicker get thicker right then the secretory phase is saying now start to develop glands start to develop glands and this is in big part due to Progesterone that we can now produce enzymes that we can now produce mucus and so forth and then what we end up getting is once these hormones like progesterone start to drop back down again towards 28 days and once estrogens drop back down again and then once follicle stimulating hormone lutenizing hormone have dropped back down again the hormones are low again at the end of day 28 and like I said the low hormones is what causes the sloughing so towards the end of day 28 we start to get that drop down again so we've got Menses which is bleeding that's happening at this stage proliferation this is all right so let's think about it like this right follicular phase is very much so due to FSH luteal phase is very much due to LH like I said FSH helps to produce estrogen right so the proliferative phase is really important uh when it comes uh estrogen is really important when it comes to the proliferative phase the secretory phase luteinizing hormone which produces ovul ovulation of Corpus Lum and ultimately produces heaps of progesterone is very much so due to Progesterone now this there's a huge amount of overlap obviously because LH is important here and FSH is important here progesterone is important here and estrogen's important here but broadly generally speaking these are the important hormones involved mostly in these Cycles or this uh these phases of the Cycles so importantly day 14 ovulation right day 28 hormone levels go low again from Day Zero they start to go back up estrogen is inversely proportional to the FSH and LH so they're going outat tropin until the estrogen levels get quite High then they both Spike that spiking of the LH maybe 24 hours before day 14 is what stimulates ultimately ovulation to occur the LH helps stimulate the Corpus Lam to produce progesterone and this progesterone as you can see will last around about 10 days right so the this progesterone is really important lasts around about 10 days is and then drops back down down why well this Corpus Lum will release the progesterone for round about the 10 days and what it's doing is it's basically said it's basically said to the egg that it's ovulated remember where's this egg now this egg has gone into the fim and has been taken in and is in the uterine tube and it's in the ampul and hopefully fertilization occurs if fertilization by sperm occurs that egg which then starts to grow and divide as it moves through the uterine tube can hopefully implant in this nice thick endometrium that's developed right in this window is here so this is we've got this important window here where it needs to implant if it and so we've got this progesterone being released to keep the endometrium nice and thick for that implantation window but if there's no sperm and there's no fertilization there's no implantation what ends up happening is that once it does if it does get fertiliz and implanted it starts to produce a hormone called human chonic gonadotropin so if it does implant right if it does implant and start to divide and so forth it will release human chonic gadat tropen basically it pretends to be gadat tropen and it is like a phone call back to the Corpus lium saying hey everything's good I'm here keep producing progesterone so if that does get implanted that doesn't stop at 28 days it keeps going that means if it keeps going it stays thick so that the embryo can develop and you don't get Menses you don't get bleeding but if there's no implantation there's no human caronic Gat tropin there's no phone call back after 10 days it stops producing progesterone and the tissue starts to diminish and sloughs Away you get bleeding that's mens's the whole cycle starts again so I hope that this helps and this makes sense hi everyone Dr Mike here if you enjoyed this video please hit like And subscribe we've got hundreds of others just like this if you want to contact us please do so on social media we are on Instagram Twitter and Tik Tok at Dr Mike todorovich at d m i k t o d o r o v i c speak to you soon