all right nja nerds in this video we're going to talk about fertilization so if you remember if you watched our ejaculation video we got to that point of where the sperm has been actually ejaculated from the actual male genital tract right and depending upon if copulation is occurring so copulation is just basically the intercourse right so sexual or intercourse between the actual female and male if the sperm is actually going to be ejaculated and placed into the actual female genital tract then we have to follow this sperm all the way to the egg well before we start talking about sperm what where is that egg actually located well if you look here here's the actual fallopian tube right and then this is the called the ampul of the fallopian tube and this is the fim of the Fallopian tubes if you remember you had the graffian follicle right and that graphi and follicle was actually popping out it was undergoing ovulation due to lutenizing hormone and popping out this secondary oosy which was freezed in metaphase 2 right so it has the secondary oosy aono poal membrane and then outside of that it had those granulosis cells so those granulosis cells which are part of the Corona radiata right and it's basically going to be sitting in the ampula waiting for the sperm cell to come and fertilize it so the seminal vesicles are one of the actual uh seminal glands that we discussed right so seminal vesicles was one so let's talk about that one first it's actually accounting for about 60 to 70% of that seminal fluid that we discussed right about 60 to 70% it's also making a lot of other chemicals that are present within there one of the really big ones is fructose fructose is extremely important reason why is it provides an actual carbohydrate source of fuel for that sperm cell another really important one is actually called prostaglandin so prostaglandins are another really really important one and then another thing that also is very very important in here is another enzyme called coagulase there's a lot of different chemicals that we could talk about in but I'm mentioning these ones because these are some very very important ones that we're going to discussed okay so that's the seminal vesicles and again he's accounting for about 60 to 70% of that seminol fluid now seminol fluid is important because it provides the transport medium for the sperm cells and it also can provide a lot of nutrients and activating chemicals the other one that we said I was I said I was going to mention is the prostate gland so the prostate gland accounts for about 30% so on average about 30 to maybe a little bit around 40 but in general about 30% of that seminal fluid it can make a lot of chemicals that are also very important one of the big one is it actually provides uh citrate citrate also can be used as a energy source okay as a keto acid intermediate it actually produces a chemical very very important chemical called fibrino liin and it's a really really interesting one I'll mention this one and it can produce a lot of other chemicals one of them that's actually kind of clinically significant is prostate specific antigen it's actually a good uh marker to determine if someone might have uh what's called BPA benign prostatic hyperplasia okay or BPH actually you call BPH so this is a good indicator of BPH benign prostatic hyperplasia okay so prostate specific antigen citrate fibery a lot of different chemicals are produced here now let's actually talk quickly about sperm like the structure of sperm and then we're going to follow this guy through so if I look at a sperm cell here let's say I actually zoom in on a specific sperm cell here and I I actually talk about a couple structures because it's actually important that I talk about it here's the head of the sperm right and in the head of the sperm you actually have the nucleus okay this is the nucleus it's going to have 23 chromosomes right it's also going to have a really important structure that we're going to talk about and it's going to be this green structure and this is called the acrosome and the acrosome consists of a lot of different types of hydrolytic enzymes like acrin and proteases another thing is right here this is actually going to be called the midpiece and the mid piece is actually made up of a lot of mitochondria so these mitochondria are literally formed in like these little coiled Manner and this is going to be consisting of a lot of mitochondr and that's the mid piece the last part is the tail and that's actually going to have fella it's basically made up of felin right so you're going to have this other part here which is going to be fella this last part here is actually going to be fella if I were to kind of just quickly zoom in on the structure of fella it actually has a lot of different things that actually make it up it actually forms this called a 9 plus two Arrangement so you have these micr tubules that are arranged in like pairs of nine all right I'm not going to draw all of them here but then in the middle it has two of them right so this is actually one that's going to make up a good portion of the actual f and a lot of proteins in between here are going to be a lot of dines and other different types of motor proteins that are important and basically helping to move the fella right and there's a basil body at the end which is a 9 plus zero in a triplet form okay but that's what's making up the flagella the tail so the tail is responsible for the the actual movement the locomotive mo mo movement the mitochondria is responsible for taking some of those nutrient sources and making ATP to help to power the fagella okay now the sperm cell gets ejaculated into the female reproductive tract right why did I mention some of these enzymes well fructose is important because it provides an energy source for the mitochondria to process and produce ATP for it to move prostaglandins are really really important let's say I draw here prostag glands look what prostaglandins does look what this son of a gun does he comes over here and he acts on the smooth muscle of the uterus he comes over here and he acts on the smooth muscle of the uterus guess what he does tells the uterus to do he tells the uterus to start Contracting but it does it in a weird way it actually causes it to contract backwards so it's called retropulsion so what it does is it actually helps to suck and squeeze the sperm cells up into the actual female reproductive tract it's beautiful design right another thing you know how I mentioned this enzyme called coagulase whenever the sperms are actually ejaculated it can easily drain out of the vagina so what has to happen is a part of the simal fluid there's this coagulase enzyme it's actually called vesiculas and what vesiculas does is it coagulates a lot of the testicular and vaginal fluid and it basically allows for this actual sperm cells to latch on to the walls of the vagina it literally is going to latch on so now this is actually going to coagulate a lot of these chemicals it's going to coagulate a lot of the actual seminal fluid and vaginal fluid and cause these sperm cells to latch on what happens to all the other sperm cells that didn't latch on they get lost out in from the vagina right so they're lost then remember I told you I mentioned fibrinol Lyin fibrin helps to be able to break up some of that coagulation and then allow for these actual sperm cells to be released from that so there's an enzyme that helps to be able to cause them to coagulate and latch onto the walls of the vagina and that's called vesiculas and then there's an enzyme called fibrin which helps to break up some of that coagulation and help to release them into the actual movement form so now it's moving okay another really cool thing about this sperm is that it has other different types of chemicals another one of the chemicals is actually called relaxin it's also in the seminal fluid and relaxin also helps to be able to help with that motility action so it it helps to speed up the motility and another really important chemical is called sop plasma and sop plasma is basically like an antibiotic chemical that destroys a lot of the bacterial cells and and other different types of microbes that are present within the female genital tract okay the sperm cell is actually moving here and it's actually moving through this alkaline fluid and you know whenever sperm is an acidic it moves slow when it's an alkaline environment it moves really fast so it moves through this alkaline environment pretty pretty fast and look what it does the sperm cell is going to get ready to start fertilizing that egg in order for us to actually see what's happening we have to zoom in on that okay so now we're going to do is we're going to zoom in on that we're actually going to take a deeper look at that so over here I'm basically drawing here an enlarged view of the oite so this is that secondary oite that's frozen in metaphase 2 right and has so this is actually the cell membrane of the oite this uh red structure is the zon of paloa these black proteins here called zopu 3 binding proteins and these are those granulosis cells that are part of the Corona radiata and then here's our sperm so here's our sperm okay and again what do we have here we had the head right here right oh another important thing is you know you should be careful whenever you're taking like you're drinking a lot of alcohol or people who are actually deficient in selenium or exposed to lead or radiation stuff like that it's actually weird what can happen is if you're exposed to pesticides or lead or lack of selenium or even alcohol look what's going to happen you're going to form some freak sperm you can get double-headed sperm multiple headed sperm so just stay away from that crap okay all right now anyway sperm's going to come here but it has to do something first so the first event that the sperm has to uh go through is what's called capacitation so what's the first event called it's called capacitation capacitation now this is occurring as it's moving generally throughout the entire female reproductive tract actually if you remember estrogen is produced around uh you know Days 1 through 14 right estrogen actually causes the cervical glands and some even some of the uterine glands to produce different types of uh you know uterine fluid and cervical fluid that basically helps to perform this capacitation reaction so what's capacitation you know on the head of the sperm it has a lot of different uh different types of proteins let's say here in this red I have a glycoprotein and let's say uh not only do I have a lot of glycoproteins here but I also have a lot of cholesterol I'll draw that here in green let's say here this green is cholesterol and I have a lot of other different types of molecules here so let's say I have cholesterol uh different types of protein molecules and stuff like that what I need to do is I need to get rid of a lot lot of this stuff I don't want a lot of this stuff here so what capacitation is is just basically cleaning off the head of the sperm so now look what happens after it under goes capacitation so it under goes this capacitation reaction and now look at it it's only going to have specifically modified glycoproteins left over so it's going to have these modified glycoproteins but if you noticed none of those other proteins are there none of that cholesterol is there we cleaned it off that event right there is called capacitation so we CLE clean the head of the sperm now the next thing that's going to happen is the sperm is actually going to start migrating and moving towards the actual zone of paluca now there's a lot of chemicals in in that these granulosa cells are producing like hyaluronic acid now what happens is when that sperm gets capacitated not only does it clean the head of the sperm but another thing it Au does is it helps the sperm to be very very motile so it actually induces what's called hyper motility so it also causes capacitation not only cleans the head cleans head of sperm by removing proteins and modifying glycoproteins removing cholesterol but it also increases motility of the sperm they call it hyper motility and now look what it's going to do it's going to beat through that hyaluronidase and all that all that hyaluronic acid and move towards the zone of paluca where is it going to bind so now the sperm cell has a specific site that it can actually bind to so that's what is this guy right there called this little guy right there that black protein is actually called Zona palucci type 3 protein so it's called zp3 receptors the sperm has specific proteins that can actually recognize that zp3 receptor so now look the sperm cell actually interacts perfectly with that so there's its nucleus and then here in green we have that important structure that I mentioned which was the acrone once the actual sperm cell binds onto the zp3 receptors what happens is something really weird this membrane opens up the sperm cell's uh membrane the top part of the head it opens up and then what happens is the vesicle of that acrosome fuses and what it starts doing is it starts releasing all the chemicals out of that acrone so it's starts releasing a lot of different chemicals what could those chemicals be it could start releasing what's called acrasin it could start releasing other chemicals like uh proteases so different types of protein digestive enzymes and what are those enzymes going to start doing they're going to start burrowing a hole through this zone of pooa so now it's going to start burrowing a hole through that zone of paluca so now we're actually moving through that zone of paluca okay so we're burrowing some holes in that zone of paluca and what is this called whenever the sperm binds with the zp3 proteins its acrosome fuses and starts releasing a lot of acrin and proteases okay this is actually called the acrosomal reaction you know what actually triggers this this chemical release it's actually this let's say I had the zp3 receptor here let's actually say here's the head specifically what's happening is once this binds on to the zp3 protein calcium ions start B running in here when the calcium ions start rushing in here that's what triggers this actual acrosome to fuse with the membrane and start releasing these chemicals okay so this is this whole event right here where the sperm cell binds to the zp3 proteins and releases these hydrolytic enzymes this is the second reaction and this is called the acral reaction okay so first step is capacitation clean your head increase your motility second step is the acrosomal reaction where you bind with the zp3 and then calcium rushes in activates the acrosome and releases acrin and proteases that digest and burough holes through the zon of paluca now look the sperm can come in and bind to these proteins here so now there's proteins on the actual cell membrane of the oite what happens is let's say we draw that sperm cell right here okay so here's a sperm cell it's actually erase this granulosis cell here we don't need this granulosis cell okay so we're going to put this protasis there so now what happens is the sperm cell has a specific protein on its actual membrane let's say it's right like this right that okay and we're going to call that protein right there it's actually called a beta unit of a protein so it's like the beta part of a specific protein there's another protein over here but it's not going to interact just yet it's not interacting just yet this is the alpha part of the protein once the beta part interacts with these proteins on the oite membrane something very special happens again it opens up specific channels on the C cell membrane okay so it opens up these specific channels on the cell membrane and what opens up what triggers this opening of the channels it's whenever the sperm the membrane of the sperm specific proteins on the sperm bind onto the oasy membrane once it does that opens up special channels and look who starts flowing in sodium ions sodium ions start flowing into the cell why is this happening because you know there's not just one sperm trying to penetrate this egg there's thousands upon millions of sperm trying to penetrate this egg you know that whenever a male ejaculates normal average is about two to five Ms unless you're some type of freak within that one mil one mil of ejaculate it can contain up to 50 to 13 milliliters I'm sorry 150 to 130 million sperm so if you produce 5 Mills you could produce potentially up to about 500 million sperm so there's not just one sperm cell that's doing this there's thousands upon millions of sperm cell doing this and then what happens so like one let's say that there's another sperm cell that's doing the same thing he's also he bound to that zp3 receptor and he's burrowing a hole right now also so he's moving through this also but this sperm cell was the first sperm cell to touch the OSI membr MBR this one was the second one as this guy is getting ready to come and bind onto the membrane the sodium ions are flowing in because this guy touch the membrane when the sodium ions flow in it creates a positive charge across the actual membrane and what that does is that blocks this actual sperm cell from binding so now the sperm cell can no longer bind to the actual cell membrane it's inhibited it's hindered from that activity this event where sodium Minds flow in and actually trigger this electrical membrane potential across this which inhibits the sperm from binding this is actually called a fast block to polyspermy all polyspermy means is just multiple sperm trying to fertilize this one egg okay so it prevents us it pro provides a fast block that's the third event okay so the first was the capacitation second was acrosomal third is the fast block the polyspermy and that's caus when the sperm touches the oite membrane with it beta subunit sodiums flow in and inhibit all the other sperm cells from attaching then once it does that then the alpha subunit binds on to this so now look now this Alpha subunit binds on to that actual protein there and then this cell membrane the oite cell membrane and the sperm cell membrane fuse and when it fuses look what happens now it can release its nuclear material out into the oite cytoplasm right so now it's actually released out here into the egg right to the ovam so now let's actually draw here let's say this is actually going to be our haid sperm cell right so he's got 23 chromosomes okay 23 chromosomes here so there's our actual so let's actually draw it like this too so this is actually the male gamet right he's pushed in one more thing has to happen because we don't want another sperm cell being able to get in at all we don't any sperm cells trying to be able to get in so we have to do one more block once this sperm cell moves in it triggers a specific action in a specific organel in this cell you see this right here this is actually going to be called the smooth endoplasmic reticulum I'm just going to put smoothe R once this actual nucleus gets pushed in this pronucleus gets pushed in okay for the sperm cell this smoothie R is activated and it starts blasting out calcium so now calcium ions are going to be produced these calcium ions what they do is they do something very special you see these like black vesicles here with these scissors you see what these like little scissor enzymes are these little scissor enzymes are a component of this vesicle this is called a lome so this is actually a lome this right here is a lome this one right here is a lome and vice versa this is also a lysosome now what calcium does is is he helps to be able to activate these lomes so now now look it's going to activate this lome this is going to activate this lome and this is going to activate this lome what are these lomes going to do now they're going to start migrating to the actual cortical part of this egg cell so now look this lome is going to come up here and it's going to fuse with the cell membrane so now look all of these lomes start fusing let's draw one right here let's draw one right here Fusion here and let's draw one right here so now look this starts actually joining here this fuses here this fuse is here and this fuse is here and it releases those little scissor enzymes remember those scissor enzymes right those scissor enzymes that we actually mentioned those are your hydrolytic enzymes those hydrolytic enzymes guess what they're going to freaking do they're going to start breaking down a lot of area so they're what they're going to start doing is they're going to start degrading the zone of paluca and breaking down some of the Zona paluca proteins so this one out here it'll degrade the Zona paluca protein and degrade some of the actual zopu in general and it'll actually Harden this cell membrane here when that happens now the sperm cells don't even have anything to attach to so what has it done calcium's activated these lomes to release lysomal enzymes out degrade a lot of the Zona paluca proteins specifically the zp3 binding proteins and all the other proteins that are making up the Zona paluca and even hardens the actual cell membrane this event here is called the slow block to polyspermy and this is the fourth and final action right and then look what happens love right this gamet right here what happens is once this calcium oh you know what else that the calcium does it also does something else really special look at this calcium it also tells this secondary oite that's in metaphase 2 finish meiosis 2 so hurry up and finish meiosis 2 when this secondary oite finishes up meiosis 2 look what happens here so it stimulates this actual secondary o like to kind of finish up metaphase 2 and then when it finishes up it under goes meiosis 2 what is meiosis to produce from this one secondary oite it now produces this new fertilized ovam so now we're going to have this new this new actual oite this fertilized ovam point right here so now let's actually draw this guy here this is actually going to be haid and this is going to be we're going to say this is our definitive so D definitive ovam the other point here of the meiosis 2 besides the forming the definitive OV them is we're going to form what's called a polar body and then that polar body will actually just get degraded by enzymes inside of the cell but this definitive ovam is the thing that we care about so now look this definitive ovam is going to come over here now so let's actually draw this definitive ovom here and this is the pronucleus of the definitive ovom and again he has 23 chromosomes but this is going to be the female gam look what's going to happen they're going to fuse and when the male pronucleus fuses with the female pronucleus now look this is going to fuse this is going to fuse and look what you get you're actually going to form your zygote you finally form the beginning point of the embryo okay conception has occurred and so now look what happens now we formed our zygote our 2N and this is going to be the zygote all right nine nerds beautiful thing here I hope it all made sense I really hope it helped iron engine nerds until next time