 Welcome back to the lecture series in animal physiology. So, we are in the endocrine and reproduction section. So, we have pretty much covered all the different hormones except the digestive hormones from the pancreas, which will be coming back after just after this when we will be starting the digestive system. So, the tail piece which is left is one of the most important piece the reproduction. What really governs reproduction? Before I kind of get into the notes and how that works I have already explained you what is a diploid cell and what is a haploid cells. And we have already went through the circuit that it is a hypothalamus which is governed by the higher centers of the brain which release gonadotrophin releasing hormone. Then these gonadotrophin releasing hormone comes to the pituitary. Pituitary releases a follicle stimulating hormone and leitonizing hormone FSH and LH. This FSH and LH surge leads to the secretion of the sex hormones by the gonads of our body. And they regulate the sexual behavior as well as sexual function of the body. So, here before I really get in the notes let us get some concepts clear. There are some concepts which has to be cleared here in the case of males. So, we all know the fertilization takes place when there is sex between a male and a female. And at the level of cells it is basically sperm fertilizes an egg. So, sperm are the male sex gametes and eggs are the female sex gametes. So, there are some very stark differences between the two apart from their structural differences. Structurally if you look at it the sperm pretty much looks like. So, sperm this is the male. So, sperm looks like something like this. It has a huge tail and here you have the nucleus and everything. And this tail is basically what it helps it to mobile. It makes it mobile. This moment is because of this tail. So, this is what we call this once again. This is the sperm which is the male sex cell. And as I explained you that these are all n. These are all haploid. Whereas the female one looks more like a roundish structure. It is like something like an egg. This is called the female and this is called egg. And basically reproduction is all about when a sperm like this fuses with an egg which is a huge cytoplasm. If you look at the size of the cytoplasm, the cytoplasm of the egg is much more larger as compared to. So, this is n female n and this is the male n which is the sperm. And when there is a cross between the two. So, basically that is how it works. Here is the egg. Here the sperm comes and there is a set of reaction here called come to that zonar reaction. When this n fertilize with this n and it leads to something called which has 2 n. This is called a zygote. And this zygote is the first cell which is formed in the mother's womb to n. This is a zygote and a zygote has two possibilities. So, if say for example, if it is in the case of male which is basically a zygote could be we call it an xx or an xy. If it is an xy zygote then this is a male and if it is an xx zygote then this is a female. So, this is the contribution. This is the male. So, the female contributes to x where is the male contribute either it could contribute an x or an y. If it contributes an y then it leads to a male and if it contributes to a male and if it contributes an x then it leads to a female. So, in other word it is whether it will be a male or a female is actually not determined by the women. It is actually determined by the male to if you look at from the chromosome perspective that is how it looks like. So, now what is so important about is this what we will be studying is this part and this part how these are regulated. What regulates the formation of this and the formation of this in the body as I have already mentioned the formation of this sperm and the egg this is the egg and this is the sperm and this is the sperm tail and sperm tail has lot of if you take a cross section of this tail you will see a lot of mitochondria out there which generates a lot of energy for its movement because it has to move a lot it is very motile structure. So, this formation of sperm is called as per metogenesis whereas the formation of egg is called the oogenesis. So, what will be studying essentially is the molecular players, molecular players regulating sperm metogenesis and oogenesis. So, after defining the problem what we are going to discuss here I will highlight two specific aspects. One aspect what I wish to highlight is that this the major molecular players in the game are the hormones which play a critical role, but there is a distinct pattern by which it regulates in the case of males as we hit upon the puberty at the age of 15 or 16 our reproductive organ of the testes they have the potential to produce hormones. In other words those testicular cells which are present in the testes they are initially they also are deployed they are 2 n, but they have the potential to divide to form n and n and then each n forms another two sets of n and n. So, each sperm cell could produce basically sorry each reproductive cell could produce four different sperms and this sperm production continues in the case of male for rest of the life there is no pretty much there is no limit. Of course, the quality of the sperm goes down as we hit upon the age of 50s and 60s the sperm quality goes down they are much more you know fragile they have chromosomal aberrations and everything chromosomal aberrations they are defects in the chromosomes because of the aging process take pitches in. Whereas, in the case of female the story is slightly different female have a limited reproductive age at the age of say 15 or 13 or 14 the reproductive age starts in other world what the reproductive and that continues up to 45 or 50 or may be extended up to 50 maximum most of the time, but there could be you know some exceptional situation but those are rare that does not happen every day you would not come across individual who are fairly reproductive at the age of 60. So, now what really does that mean for the males I told you we can produce a male can produce a sperm for all his all his life. So, the female every month one egg matures and that one egg is capable of fertilizing a sperm or a sperm is capable of fertilizing that egg. So, every month that that monthly cycle of a maturation of a egg is called menstrual cycle which a female undergoes from the age of say 14, 13, 14 or 15 all the way up to 45 to 50 and that is the phase when a female is reproductically or reproductically active other than that after that it seizes that whole process of menstrual cycle seizes and they do not produce any fertilize eggs after that. And what is essential here to highlight is that it is a very cyclic phenomena in the case of males across the month or across the years and across the whole life once they ate upon puberty they can produce a sperm, but in the case of females it is a very very cyclic fashion there is a regulation of say 21 to 28 days when every depending on the female it could it could may be even up to say 18 days to 28 days to 31 days depending on which where I mean it could be a Caucasian female it could be a Asian female it could be an African whatever depending on the individual race or place from where the female belongs to their menstrual cycle varies it could be 18 days to 31 days and during this phase what we will be actually highlighting is that during this phase there is a cyclic fashion of secretion of those gonadotrophin hormones specially the FSH LH follicles stimulating hormone and leitonizing hormone and that is what regulates the whole cyclic process and the tail end we will be talking about when the egg gets fertilized when a women is ready to give birth when the zygote is formed how this cycle gets stopped and till the child is not born that cycle remains stopped and how that takes place that is what we are going to discuss. So, talking about this we will talk very briefly about the male situation what happens in the male in the case of the production of this sperm as I told you in the males continuously FSH and LH is being produced LH is being produced this concentration in F of SH and LH remains fairly constant and as I have already told you that there are lytic cells in the testes. So, testes is structure is something like that and this is where these different cells are being produced. So, testes are the one which is responsible for producing of the sperms. So, there are lytic cells which support in this whole process FSH and LH helps in the maturity of these sperms everything. So, this is how the male sex production takes place where there is not much complexity it is much more simple and there is no cyclicity it is all throughout the reproductive phase it goes on and it may goes on for the whole life. But best quality of a sperm comes at the age of like in 20 to 35 or 40 when the best quality which are healthy sperms which has the ability to fertilize the female egg and lead to the production of a healthy baby remains in that age. Now, talking about the female which is I told you that this is the very cyclic phenomena. So, let us talk about what is happening in the case of females in the case of females. So, let us again get back to the circuit. So, you have hypothalamus I am repeatedly drawing this circuit to kind of you know keep the exact track of how this whole circuit is functioning anterior pituitary and then you have the ovaries where these are acting. So, these are GNRH Gunnarutrofen releasing hormones and anterior pituitary is releasing FSH and LH and this FSH LH acts on the ovaries and leads to the production of different sex hormones. So, what we will do now we will talk about two aspects here. We will talk about menstrual cycle which I have already mentioned last from for some it is 18 days to up to 31 days and what is this cycle this is here is the important part is the cyclic fashion and we will talk about the fertilization what happens after fertilization. These are the two aspects what we are going to deal in the reproduction. So, we have already talked about the production of LH and LH. So, LH and FSH. Now, let us start with what I will do I will talk about four parameters. So, assume a cycle is happening in a female. So, before I get into the cyclic thing let me explain something else here. So, how that maturity is taking place. So, initially what happens you have something called a primary oocyte is something like this. This is a primary oocyte. So, I am in the oogenesis now primary oocyte then primary oocyte leads to the formation of something called a secondary oocyte. Where the cytoplasm increases in the egg these are the secondary oocytes. Secondary oocytes leads to the formation of something called a tertiary follicle this is called a tertiary follicle. From the tertiary follicle this whole process of formation of primary to secondary to tertiary follicle is governed by this whole maturity is governed by FSH follicle stimulating hormones which is essentially is responsible for the maturity of the follicle. After this what happens and this it does so because FSH leads to the secretion of estrogen. It is the estrogen which is secreted by these cells in the ovary which leads to the maturity of this from primary secondary to tertiary. After the tertiary is are formed that it leads to the another level of maturity which is basically called formation of graphene follicle. So, continuing from previous one graphene follicle and from graphene follicle because of LH surge, luteinizing hormone. So, we have talked about the other hormone the FSH. FSH is involved in all the maturity part then comes the role of the luteinizing hormone. What luteinizing hormone does is that it leads to basically this part is released. This egg is actually releasing the eggs releasing the egg and this releasing phenomena is something like this. We have here the egg is getting released and this process is termed as ovulation. So, this whole process by which from primary to secondary to tertiary to graphene follicle to the release of egg falls under something called ovulation. This whole cycle up to ovulation and after ovulation falls under something called the menstrual cycle which we are going to discuss now. What exactly is happening and how this whole process is taking place. So, now what I will do I will just check out that now I will draw how the surge of follicles. So, this whole process if you look at it if you just think before I draw all the graphs and really show you. So, this whole process if you look at it very carefully is happening. There is an FSH which is coming which is leading to the maturity of the primary follicle to secondary follicle to tertiary follicle. Then there is a surge of the next hormone which is a luteinizing hormone that comes and that leads to the egg to be released from the follicle. That process is taken care by the LH and LH does. So, by making those cells to secrete another hormone which is called progesterone. So, in other word we are dealing with four hormones here FSH LH which are secreted by the pituitary step one. Step two there are of course, let us talk from the even top that hypothalamus secreting gonadotrophin releasing hormone gonadotrophin releasing hormone at pituitary it is secreting FSH and LH at the third level. Because of the surge of FSH and LH there are two more hormones which are secreted which is estrogen and progesterone. So, in other word we are talking. So, what we will be seeing in the case of female how the FSH level changes over a period of a cycle of a menstrual cycle how the LH level changes these two from pituitary and then at the gonads we will be talking about the change of the profile of the estrogen and the progesterone. So, in other word there will be a graph which will be showing four different lines of cyclicity by which it is changing and top of that what are the physical changes happening in the body in terms of body temperature basal metabolic rate and behavior. So, we will be talking about. So, you will be now what I will be drawing I will be drawing four graphs showing the way the FSH level shifts the way the LH level shifts the way that leads to the secretion of progesterone and the way it let leads to the secretion of estrogen. So, let us draw the graph and that will help you to appreciate this whole process and simultaneously what I will do I will draw all the concentration how that is happening. So, let us divide this say for example, let us talk about an average cycle of 28 days. So, day 1 day 7. So, underneath I have what I am drawing is the day 7 day 14 day 21 and this is day 28. So, we are taking an average female who has a cycle of 28 days this is the cycle fine. So, after every so basically what is happening is this. So, let us divide the phases this is called menstruation phase menstruation phase then the next phase is called follicular or proliferative phase follicular or proliferative phase then on day 2 into 1 this is called luteal phase luteal luteal luteal secretory phase these are the different phases. So, now what I will do I will divide the graph into 5 different parts which will help you to appreciate it in 1 go 1, 2, 3, 4, 5. Now, the first graph will be talking about from the pituitary at the level of pituitary. So, let us get the scale right. So, at the level of pituitary we are talking about like you know 1, 2, 3, 4, 5. So, highest limit is 50 and the unit is. So, here this is 0 1, 2 just assuming units per liter. So, this is the level of the anterior ap anterior pituitary FSH and LH in the blood these are all done in the blood. So, I am marking FSH with red and I will be marking LH with blue. So, let us talk about how the FSH is shifting right. So, the FSH shift is something like this it has a basal level somewhere here and then the FSH goes down like this and as we reach somewhere out here FSH level picks up and then it slowly goes down and again start for the next cycle. So, here begins the next cycle from here on the next cycle begins. So, this is how the FSH is shifting. So, if you kind of look at it at sometime out here sometime out here in the case of 20 days cycle. So, one more thing I will wish to highlight I will come back to this graph and say. So, depending on your days like if the cycle is of 18 days if the cycle is of 28 days or 31 days the date of evolution changes. So, in case of an average 40 28 day cycle the evolution generally takes place at the time of 14th day 14. So, now if you come back to the graph you will say that the major rise took place around day just before day 14 out here. So, if this is 7th day this is day 14 this is this is day 14. So, just before day 14. So, this is the evolution that is why I marked it as a red circle this is the evolution phase when it is taking place. Now, let us see how the L H is going L H simultaneously L H remains fairly low all throughout and then it is starts picking up here and it reaches somewhere like this it reaches the highest peak and then it starts falling down again and goes down like this. So, if you look at it around day 14 which is here out here L H is maximum. So, as I was telling you there is a cyclic fashion. So, the F S H just before day 14 F S H hits the peak and then followed by with a slight delay out here look at this small delay then the next peak starts. Now, simultaneously what is happening because we know F S H leads to the secretion of now let me F S H leading to the secretion of your estrogen or strudel whereas, L H leads to the secretion of progesterone. So, now we will define how these two hormones are changing their profile. So, their level is if in this graph. So, again put the amount which is essential. So, they are far more low 0.4. So, this is microgram per liter of blood. Now, this is the strudel level and compare to strudel the estrogen level is higher. So, if I have a corresponding corresponding. So, let us pick up two colors first. So, I am putting estrogen as in green and I am using a gray color for progesterone. So, the progesterone level is higher actually progesterone level if I have to draw a graph progesterone. So, that will be like you know the top thing will be 16 microgram per liter. So, progesterone level progesterone secretion is much more higher as compared to estrogen level. So, if you tally this what happens now let us talk about what is happening to the estrogen how the estrogen behaves. So, the estrogen level moves like this and as you could see where this one is picking up estrogen level exactly picks up fairly close to it and then there is a small hump and then it goes down like this. So, if you tally estrogen level estrogen is close to the same peak of as almost the same peak as the FSH because FSH stimulates the secretion of estrogen. So, that is why you see they are in close sync FSH leading to the secretion of the estradiol or estrogen. What happens next now let us talk about the progesterone level now the progesterone level this is just like your LH that remains fairly low out here and mind you the progesterone secreted a fairly high amount and as it reaches and it remains like that almost up to day 14 and then there is a rise in progesterone big time out here and that continues and then it goes down. So, the progesterone level here you see the peak of the here you see the peak of the leutanizing hormone and here you see the peak of the progesterone. So, if you look at this cyclicity the FSH out here FSH here you have the LH here you have the estrogen and here you have the progesterone. This cyclic fashion continues month after month during the reproductive phase of a women and this cycle is actually called the menstrual cycle, but in this process. So, this is what you are saying what is happening inside the body these molecular players are changing their concentration, but there is something else which is expressed every month there is a blood discharge from the women body in the form of menstrual discharge that menstrual discharge is nothing, but the process by which a female rejects the unfertilized egg from the body and this process what we are going to deal now is I will tell you I showed you this diagram just before this. This out from primary secondary to tertiary to the whole process. So, now I will explain it in terms of where exactly this thing happening. So, now we will talk about the follicular development let us come back to the follicular development with respect to this follicular development or you can call it a part of the whole game of called ugenesis the process where this. So, what essentially is happening at this part of the graph basically you have a immature follicle like this what I draw is the primary follicle immature follicle. Then during the phase 2 out here there is a maturation of follicle maturation phase and it is at this phase out here. So, I have to say if I do just put 2 days back and 2 days forward and this is called the ovulation phase this is very critical phase ovulation. And then comes after the ovulation if the egg is not being used for fertilization then this is lost it form something called corpus luteum and this is degenerating corpus luteum and it is at this phase out here if you look at it. So, it is at this phase when a new cycle starts basically this degenerated corpus luteum is being discharged out from the body. And what really this ovulation phase this is on the most critical phase this is the phase when a female is reproductively active this is in other words those during in the menstrual cycle that phase when a female sexual activity is at its highest. That particular balance of L H F S H progesterone and estrogen is a unique phase of 2 to 4 days when a female is a reproductively active. This is the time if this egg which is formed is fertilized by a sperm at this weight. If a female has a sex with a men and this is the time if it is fertilized. And this there is a possibility that this egg will become a zygote after fertilization. So, this critical window if I just I am shedding it is the most critical window in all the menstrual cycle in the complete menstrual cycle in terms of reproduction ability of the women. So, in other word you can translate it back in terms of if you look at the female cycle. So, every year a female has every month if I look every if let us start from the month every month there is a window of 2 to 4 days when a female is able to fertilize as the the egg has the ability to get fertilized by an sperm. So, every month technically there are only 4 or 5 days or 3 you can call it 3 to 4 days window when a female has potential to fertilize its egg to produce a zygote and eventually a baby. So, in other word if you look at it the actual reproductive activity of female over a period of year will be around 48 to 60 days that is it every month and other than that at any phase if a female is having a sex on any other phase other than this if I go back any of these phases most unlikely hood that could lead to a formation of a baby. But, this is the phase which is very critical for you to understand and this is a very very cyclic and very well tuned activity and if you look at the way the basal body temperature changes which I wanted to show here once I can. So, the basal body temperature remains. So, let us talk about an average temperature that is moving like this, but at this phase basal body temperature goes fairly high and then it falls down. So, this is the zone when the body temperature of a female goes fairly high because of the action of these different hormones which are there and metabolically it is very very active. This whole cyclic process is many a times disrupted, but I was I told you in one of the previous classes on endocrinology that please look for the endocrine disruptors and all those kind of drugs and many a time because of imbalance of other hormone the cyclicity of several women they suffer from lot of gynecological disorder in terms of because this whole cycle is being disrupted they do not get the proper menstrual cycle they do not get the men's in right time and it kind of leads to a lot of complications and lot of irritability lot of behavioral trait which are very asynchronous behavioral traits which happens, but if you translate it without getting emotional you translate it in terms of the hormonal you will realize it is a very tightly scheduled molecular event which is taking place within the body of a female and any disbalance or you know in a shift from that kind of tightly regulated chemical phenomena could lead to a whole array of behavioral changes which we really cannot explain straight away that needs a lot of probing. So, this is very important I expect you people to appreciate this whole thing that this is a chemical game of three or four players.