Animal Reproduction

Hi. In this lesson will be talking about animal reproduction, which often is going to be sexual reproduction, which is when two organisms combine their genetic information, usually through the fusion of GAM. It's now gametes are formed from my oh sis. And these are going to be, uh, cells that have just one copy of each chromosome from the parent making them hap Lloyd. Now, if this sounds an unfamiliar, I recommend you go check out our videos on my Asus and sexual life cycles. Now, male gametes are no nas sperm and female gametes air. No nas eggs. Male gametes usually are smaller and motile, meaning they can move themselves. They can propel themselves. Female gametes tend to be larger and non motile, meaning they can't propel themselves. Now we call the fusion of sperm and egg fertilization, and this will form a zygote. So we will get a zygote from fertilization and that zygote is going to be deployed, meaning it will have two copies of each chromosome one from each parent, thanks to those gametes, each being half Lloyd. Now, some organisms reproduce through a sexual reproduction, and this is when offspring arises from a single organism and it on. Lee receives genes from that parent. Now there are a few ways this can occur. One is butting, which is when on organism will kind of grow off of its parent and break off when it becomes mature. You can see that happening in these yeast cells here. Yeast are, um you know, eukaryotic organisms, and they reproduce by budding. You can see this parent cell has this bud growing off of it. So does this one. When these buds air mature, they will literally break off from their parents sells. This also occurs in the animals hydra. They also reproduce through budding. Now fission is when an organism divides into two or more parts. And this is how, for example, bacteria reproduce. Uh, this is known as binary fission and bacteria, and as you can see, it's going to lead to to genetically identical organisms. Now parthenogenesis is a very interesting type of a sexual reproduction because it's when growth and development occurs without fertilization. You see this in, for example, some species of lizards which are going to be all female, and we'll just grow and develop offspring in the app without any fertilization and those offspring will, of course, be female. So you might be wondering, what's the point of sexual reproduction? Because it's mawr energy intensive, and it's less efficient than a sexual reproduction. E. Look at this little graphic behind me. A sexual reproduction like we can see here, is going to lead to much greater increases in the population size. So what's the advantage for doing it this way? You can't increase the population size nearly as efficiently. It also requires two organisms just to produce one new offspring. Or, in the case of some organisms, you'll produce multiple offspring. But you get my point. It requires to parents to get together to generate any offspring. So what's the point? Well, one explanation for this is known as the Red Queen. Hypothesis and theory. Idea is essentially genetic diversity. Organisms that reproduce a sexually don't, um, have a harder time introducing genetic diversity. Let's say they have to come up with other mechanisms to do that. Aside from these a sexual reproduction methods, sexual reproduction naturally has naturally confers genetic diversity to the population. This is important because the Red Queen hypothesis says that organisms have to constantly and adapt and evolve to compete with the posing organisms. This idea comes from a quote from Alison Wonderland from the character known as the Red Queen. When Alice is talking to her, she says that you know where I come from, not Wonderland. When you run, you get somewhere. You know, when you move, you actually get to some place, and the red queen says Now, here you see, it takes all the running you can do just to stay in the same place. And that is why this is termed the Red Queen hypothesis. It's because organisms have to constantly be running right, adapting and evolving, which is why sexual reproduction is favored because it introduces genetic diversity that promotes that adaptation and evolution. And this is necessary because they have to compete with all the other organisms around them that are also constantly adapting and evolving. With that, let's go ahead and flip the page

Hello, everyone. In this lesson, we're going to be learning about reproductive anatomy. But specifically in this lesson, we're talking about male reproductive anatomy. In the next lesson, we'll talk about female reproductive anatomy. Okay, so let's get into our lesson. Okay, So genitalia is just the word that means sex organs. This could be anything on the organism that is used for reproduction. Now, the gonads specifically are going to be the organs that produce gametes, egg and sperm. And since we're specifically talking about the male reproductive anatomy, we're going to be talking about sperm production, where it happens and the different parts of the male anatomy. So the test is are going to be the male gonads, and they're going to produce sperm, and they're gonna have these many different components. As you guys can see here. It's really complex inside of a testes. And there are a lot of different areas that sperm traveled thio in their method of production. So in each space, more and more is added to them or their stored or their matured in a unique location. Okay, So before we get into the tubules that are used in the test ease we're going to talk about the scrotum, which is going to be a skin pouch that holds the test ease. This is gonna be a characteristic that's found in almost every single land mammal. I believe the aquatic mammals, like whales and dolphins, are not going to have this. This is going to be a structure that is outside of the body in land mammals, and you guys know what it's for its to maintain the correct temperature off the test is to ensure that the sperm is able to be produced. Now we know that the internal body temperature off most mammals and humans included is going to be around 98 degrees now for correct sperm production. It actually can't be 98 degrees. In fact, it has to be 95 F for sperm production. If it is too hot or if it is too cold, the sperm will not be produced properly, so the scrotum is used to keep. The test is outside of the body so they don't get too hot, but still close to the body so they don't get too cold. So they're a perfect 95 degrees, because if they're not within that temperature. Sperm are not gonna be produced properly. And then that male won't be able to produce Reproduce. Okay. All right. So now we're gonna be talking about the Semin efforts tubules and the epidemics, which we're going to be two major types of tubes that are used to produce sperm. So the Semin efforts tubules are coiled tubes in the test ease where sperm are produced, they're very important. So as you guys can see in this picture, there going to be these tubes that I'm highlighting in yellow. And I have two different diagrams for you guys here, and these are going to be the tubes that actually form the sperm. So let me label those Semin if Iris to Buell's are going to be right here, and this is going to be where the production of sperm actually happens. But sperm are not fully ready and fully ready to go out of the seminary. Fris, tubules. That's actually multiple steps. And in the epidemics, this is where sperm are going to mature and they're stored. And the epidemics I'm gonna highlight in blue is gonna be this structure here. The epidemic is going to be where the sperm actually become mo tile. They're given all of their correct components, and now they can actually swim. So while sperm are in fact made in the seminar first tubules they're not swimming. They're not fully formed. They're not matured. They'll move into the epidemics, which I highlighted here in blue. And then they become mature and they're stored. I believe they could be stored in the epidemics for 2 to 3 days, but then they will be released. Any new batch will come in now. The epidemics. Crazy fact about the epidemics. This is actually not one solid structure. It's a coiled tube that's coiled around itself. And if you uncoil the epidemic, it could be 6 to 7 m long in human beings, each one which is insane. And that's crazy. It's so long yet it fits in this small little package, So those are gonna be the two major types of tubules that are used for the production and maturation of sperm. Now, if you're wondering what this tube you'll is right here that I'm highlighting in pink, this is going to be the vast difference which we will talk about a little later in the lesson and the vast difference is gonna be important because it's going to transfer the sperm from the testes itself. So this is going to be basically the passageway out and you go the seminar, first two bills to the epidemics to the vast difference. And then it's going to go into the Yuri threat, and then it's going to leave the male body. So let me label the epidemics before we finish this section. Yep, nope. Epidemics is right here in blue. Now there are different sections of the epidemics, which I'm not going to teach you guys about, but there's ahead of mid section in the tail. If you guys would like to look that up, you certainly can. It's just the different regions of the epidemics, different areas where the sperm actually matures. OK, so now let's go down and we're going to talk about the primary genitalia. So the internal genitalia of a individual is the secondary genitalia. So this is going to be the test ease and the males and the ovaries in the females. The external genitalia is the primary genitalia, and in the males that's going to be the Penis, which is the male sex organ, and it is going to be used for internal fertilization. They're gonna be many different components of the Penis. There's going to be the gland. The prep use. The pre abuse is actually what is removed during circumcision whenever a boy is born, if the parents choose to circumcise the boy, that is going to be where the profuse is removed. And this is just the protective skin around the Penis. Now the urethra is going to be found inside of the Penis. And let me show you guys, it's down here. It's gonna be this too bright here. Wrong color. It's gonna be this tube right here. Now the urethra is not on Lee used for urine. It's also going to be used to transport semen as well as you guys can see here. Urine and sperm and then some organisms. But humans not included have a back you'll, um, and this is going to be a bone that is inside of the Penis. And it's in the majority of mammals. Humans air pretty much an exception. There are a couple other organisms that don't have this, but most mammals actually do have a vacuum But for some reason, humans have no need for it, I guess. All right, So now let's talk about the different fluid. So semen is going to be their male reproductive fluid, and that's kind of interesting because it says containing sperm. Ah, lot of people think that semen is Onley sperm, but in fact it's not. It has sperm in it, but it's got a lot of other liquids as well. So that's why they call it the male reproductive fluid, because it's not just those sperm cells, and the sperm cells need these other fluids because they can't survive without them. Through other fluids that air in semen allow the sperm to swim. It gives them nutrients. It has enzymes in there for them, and it's really basically their protective fluid that they live in. Okay, so whenever we're talking about semen, it is going to be produced in different areas, right, because there's different components of the fluid. They're gonna be produced in different areas. Now the seminal vesicles produce a fluid containing fructose and mucus, and this is going to be basically like fructose a sugar right. This is going to help these cells have the energy to swim. Now there's also the prostate gland in the BULBUL. You'll re throat. Can't say that one prostate gland and bulb you'll re throw gland. I butchered that. I'm sorry, guys, and these are also going to secrete fluids into the semen. And the prostate actually makes 30% of the fluid that is used for semen, and it doesn't contain sperm, so that's a lot of high percentage that actually doesn't contain sperm. Now the prostate gland is going to be a gland that you guys can see right here. And the prostate gland can be quite problematic. For most men, it is the gland, or the area of the body that has the highest rate of cancer in men in a First World country. So in the United States, whenever you're talking about cancer specifically in men, number one cancer in men is going to be prostate cancer, and that's going to be this gland here that helps with the movement of sperm, and it helps with creating the fluids in the semen. Okay, and then the movement of sperm out of the male body is of course, going to be ejaculation, and it goes from the Semin Ifor's tubules to the epidemics to the vast difference. And then it's going to be expelled through the urethra. Now, whenever it's moving from the epidemics to the vast difference, it's on Lee sperm at this point, and we never it goes into the urethra. It's going to be mixed with all of the other fluids from the different glands that produce those fluids, like the prostate gland. Okay, now, I told you what we're going to talk about the vast difference a little later in this lesson, and we certainly are. And I already told you the vast difference is going to be a duct which connects the ejaculate Torrey duct, and it's going to connect it to the testicles. And this is going to allow the sperm to actually have a path to travel out of the male body. Okay, guys, and remember, I talked about all these different components of the semen. Those are all going to come together in the ejaculate torrey duct before they're exiting the body. Now we're looking at all of this information, and this is gonna be a side view or a lateral view of all of this anatomy and I wanted to tell you guys that the bulb Oh, you're you're re thoroughly gland is also called calpers gland, which is over here. So if you were missing that particular gland on this image, it goes by a different name. I'll write that down for you guys. So this is also the bulb. Oh, you're re throw gland. It just has two names. And I believe Cal Per was the man who discovered that particular glance. So they named it after him. So you guys can see that we have the test ease down here, and then they are going to have the epidemics and the vast difference which you're going to lead out of the test ease and into the body. And you guys can see that we have what we talked about. The ejaculate Torrey ducked the seminal vesicles, the prostate gland, the bulb. Oh, you're Ethel Gland or the calpers gland and all of these things. They're going to be in here, and they're basically going to help the semen leave the body and we have the urethral opening. And let's see, what else do we have? Just that we talked about because some of the stuff we didn't actually talk about and plans for skin. I believe those were all of the things that we talked about, remember I told you the foreskins also called the preview. So if you were looking for that, that's gonna be where it iss Okay, I've highlighted all of the things I believe we talked about. And I wanted to show you guys the path that the sperm would take its built here, and then it would travel up. And then it would travel into past the seminal vesicles past the prostate gland into the ejaculate. Torrey ducked. The prostate gland is used to push the semen out and then out through the urethra. Now, you guys can see the uterus also attached the bladder, because that is going to be the way that you're in. Also exits the body. Okay, everyone, I hope that was helpful. Next, we're going to go on to the female reproductive anatomy

Hello, everyone, In this lesson, we are going to be talking about the female reproductive anatomy. Okay, so let's get into the lesson. And first off, let's just go over some major anatomy pieces and then we'll go into more detail. Okay, so first off, the ovaries are incredibly important for female organisms because these air going to be the places where they actually make the eggs. The female gammy. So eggs, they're going to be made in the ovaries, and they're going to be released periodically. Something interesting to know about female organisms and human beings. Included is that a female, when she is born, already has all of the eggs that she will ever make in her entire lifetime. And it's just that all of those eggs air held and then periodically released throughout her entire life and whenever she is no longer has enough eggs or she's no longer periodically releasing those eggs that individual go into menopause. But the ovaries hold all of the follicles, which create all of the eggs, and all of the eggs are already produced before the females actually born. So she has all of her eggs for her entire life. The moment she is born. Okay, so we know that these eggs are periodically released from the ovaries, and that's going to be during the process of ovulation. And whenever an egg is ovulating from the ovaries, it is going to travel down the overdose. Oct. Now different organisms have different types of over ducks. Organisms that lead that actually do external fertilization or actually, um, have their eggs leave their body are going to have over ducks. We have internal fertilization, so our over ducks don't lead to the external environment. They're going to lead to the interior of the woman's body into the uterus. So these were going to be called something a little bit different. They're going to be called the fallopian tubes thes air mammalian over ducks that actually don't lead to the exterior of the body but lead from the ovaries to the uterus because the fetus develops inside of the female. Now that leads us to talk about the uterus. The uterus is going to also be called very commonly in human beings. It's also called the womb. But what I want you guys to know is it's this hollow muscle structure and its main job. Its main focus is to be a place where the fetus actually develops. Okay, everyone. Now the opening to the uterus is gonna be called the cervix, and the cervix during childbirth is actually going to greatly dilate. If you've ever heard of a woman being six centimeters dilated or a certain number of centimeters dilated, we utilize that information the dilation of the cervix to know how close it is to the time of childbirth. And in fact, the cervix should dilate to about 10 centimeters at the time of childbirth. So the cervix, usually quite small, is going to be what opens up and allows the baby to leave the uterus. Now there's also the lining of the uterus, which is incredibly important. And this is called the endometrium, and this is going to be the inner epithelial tissue of the uterus. And this is going to be what is going to change with each menstrual cycle. And it is going to be where the egg or the zygote, I mean, actually implants into the wall of the uterus that's going to be on the endometrium tissue. Now. There are many different tissues that make up the uterus. You can see the endometrium here. Then there's the my oma tree. Um, and the pair, um, a tree. Um, the endometrium is going to be the innermost one, and it's probably going to be the most important for this lesson because that's where the zygote actually implants. And this is going to be the tissue that has shed during menstruation, and it can also form the placenta. If the woman does become pregnant, you may have heard of endometriosis. This is going to be conditioned in some women where the endometrium actually will grow outside of the uterus, and this can be incredibly painful to some women. So endometriosis deals with the endometrium, or inner layer of the uterus. And that's when it's not growing correctly. And it can cause pain. So you guys can see that this is going to be a diagram. Let me scroll down so you can see the other, um, labels here. So this isn't going to be the basic diagram of the female genitalia, and you guys can see that there are two ovaries, one here and one here, and they're actually going to connect to the fallopian tubes, which you guys can see right here and these fallopian tubes air going to lead into the uterus. And that's where the zygote will implant and the fetus will grow. And then here we have the cervix, and this little area right here is going to greatly dilate. And it's going to allow the baby to pass from the uterus to the vagina and then out of the mother. And that is the process of childbirth. Now let me scroll down. This is going to be the same diagram right here. It's just showing you the position of the female genitalia in the woman. And you guys can see that it's just basically in the pelvic region. And a woman is gonna have to ovaries on each side of her pelvis, and then she's gonna have her uterus and all that stuff in the middle. Okay, All right. So now let's talk about the rest of the anatomy. So let me scroll down a little bit so we can see what we are looking at. Okay, so then we're gonna have this is going to be the rest of the anatomy. Andi, the vagina is going to be the muscular opening that comes before the uterus. You guys can see that. That's this right here. And the uterus is going to be what I'm highlighting in pink. You guys can see that the uterus is incredibly muscular, and it's gonna have a lot of tissue that is there to support the growing baby. Now the vulva is going to be composed of two different pieces of anatomy. But basically what I want you guys to know is these air the external features of the female genitalia. And they're mostly they're just to protect the female genitalia from basically the outside world. So you have the labia majora, which encloses and protects the rest of the vulva. So the very outside and then you have the labia majora, which encloses the vaginal and urethral opening. So basically, it's just to cover everything up and make sure that it stays safe. And then you're gonna have the clitoris, which is going to be the female form of erectile tissue, and you guys can see all of that in this really good image. I really like this picture because it it shows you from the side view while the one up here shows you from the straight on view, but we always see that view. And I like this one because it shows you where everything is located in relation to everything else. So you guys can see that up here is going to be one ovary, and then you guys can actually see that the egg is going to travel down this tube right here into the uterus. So you guys can imagine that if a sperm is going to fertilize an egg, how far does it have to travel? It actually has to travel all the way up into the uterus. And then you guys may or may not know, but fertilization generally happens inside of the fallopian tubes, so it has to travel a really long way. So that is going to be the basis of the female genitalia. Okay, everyone, let's go on to our next lesson.

Okay, everyone. So in this particular lesson, we're going to be learning about Damita Genesis. But in particular, we're going to be learning about Amita Genesis specifically in the mail organism, which is the production of sperm because commedia genesis is going to be the production of gametes and sperm is going to be the male gametes. Now, we have all of these different cell types, and they're going to be the sperm Atago, Nia, the primary sperm a decides secondary spur, Mattis sites permitted and spermatozoa. And all of these are gonna be very important for the production of sperm. And the production of sperm is going to be called sperm a genesis. Now, whenever we learned about give me to Genesis, we simply learned about my oh, sis, right, That one cell divides twice and creates four hap Lloyd cells. But unfortunately, it's not that easy. And we're actually gonna have mawr cells doing the division in sperm a genesis. So first off, you're gonna have these sperm Atago nia cells, which you're going to be these undifferentiated cells in the test ease of the male organism, and they're gonna have to undergo might Oh, sis, before they're actually ready toe, undergo my, oh, sis, and form the GAM. It's. And once they undergo my toe sis, then they're going to turn into these primary for Mattis sites, the primary spam Mattis sites are deployed cells that are completely ready to go through my Asus. So the primary spur Mattis sites are going to be found in the semen avoris to Buell's, it's always hard for me to say, and these they're going to be to Buell's that air found inside of the test ease, and they're gonna be very important for sperm a genesis, because this is where it's actually going to take place. Then, once the primary spur, Mattis sites go through one round of my Asus or my Asus one. Then they're going to turn into these secondary sperm Mattis sites, which are then going to be Hap Lloyd. Because remember, at the end of my Asus one, the cells that air produced are Hap Lloyd. So the secondary spur Mattis sites are hap Lloyd, and they're going to undergo my Asus to the second round of my Asus, and they're going to turn into these sperm it'd, which are undeveloped male gametes. So whenever we think of my Oh, sis, we think the end product is simply these perfect GAM. It's so you would assume that their sperm, but unfortunately they're not. They have to go through a couple more steps to make them into mature sperm. So the immature or undeveloped sperm that are made from my, oh sis are gonna be called these sperm, It'd and they need to undergo more maturation to become the sperm, which are also called spermatozoa. So these were the motile sperm that we think about whenever we think about male gametes. Okay, Now these these processes I have a diagram down here which I'm going to go through so you guys can see what I actually talked about whenever I talked about these particular divisions. But first, I want you to know that the sperm are gonna have these two really important structures that compose them. They're gonna have something called the akra Zone and they're gonna have their flu. Gela, their flu. Jealous, probably pretty self explanatory. This is going to be there micro tubules tale that allows them to swim. And we all know what that looks like, right? And then we're gonna have the Ark a zone, and this is going to be the cap off a sperm cell, and it's going to be used to help digest the outer layer of the egg. And it's really gonna help that sperm actually get into the egg, which we talk more about whenever we learn about fertilization in later lessons. Okay, everyone All right, So let's go down and let's have a look at the actual process that takes place. So that on that outside of the lesson is actually going to be the process of all the different cell divisions that actually make these sperm gametes. So remember, you have these sperm at Ogoni, Um, and they're gonna have to undergo mitosis because they're not entirely ready to go through my Asus quite yet. So the sperm at Ogoni themselves are going to go under my ketosis and create the primary spur. Mattis sites which you guys can see are deployed. So these deployed cells are ready to undergo my Asus one, and then they're going to turn into the secondary spur Mattis sites, and what is going to be deployed E of these secondary spur Mattis sites thes secondary spur Mattis sites are going to be happy, Lloyd cells. Okay, everyone. So these air Hap Lloyd cells because at the end of my Asus one, the cells air Hap Lloyd and then they're going to undergo my Asus two and create the sperm. It'd remember the sperm. It'd Czar Hap Lloyd, But they're underdeveloped. Gam, it's They're not perfectly made yet. They need some alterations, um, maturation. And through the process of sperm, E o Genesis, which is that maturation of the sperm. Then you're going to get what we think of as actual sperm with their tails and their arcas own. So you have to actually add some other pieces, like the flag Ela and the arcas, um, to these sperm a Tibbs to create spermatozoa. Okay, everyone. Now here I have this nice diagram off a sperm, and if you guys were wondering what the Ark is, um actually looks like it's right here and it's depicted in yellow, and it's going to be the cap on the head of the sperm. And like I said, it's going to be used to actually get into the egg, which is actually a difficult process. Okay, guys, Now the other components of the sperm are, of course, going to be the nucleus because that's where it holds its hap Lloyd genetic material that will then fuse with the eggs Hap Lloyd genetic material to make a saigo and then really interesting right here. You can see it says mitochondria in this box that I'm drawing are going to be ah, whole bunch of mitochondria. I believe it's 75 to 100 mitochondria. And do you guys know what they're going to be used for? They're going to be used to power the movement off that flow. Gela. Remember, mitochondria are utilized to make a teepee energy, which you can use to do work. And the work that needs to be done here is going to be the movement off the tail of the sperm. So that's why you have the mitochondria right at the base of the tail so they can power the movement off that flag. L a tail. Okay. Now, what is this part right here? Do you guys know? Well, this is a flow, Gela, right? And whenever we learned about the site of skeleton, we learned that flow Gela are going to be made of micro tubules. So let me spell that right micro tubules and specifically remember, they have a unique structure. They have a nine plus two arrangement off micro tubules. So of MTs. It's just how I'm going to write it, because it's the shortened way to write it. And do you remember what motor protein they use? Remember, they're going to use the dining motor protein so they have a nine plus two arrangement of micro tubules with the dining motor protein. And that's going to be this particular structure that you see here. This is a cross section, and it's gonna have the nine exterior micro tubules and the two interior micro tubules and the dining proteins that move that flag. Ella. Okay, all right, so that's going to be the basic pathway that you utilize to create sperm. So now let's go down and let's talk about the important hormones that we have that actually help with the creation of GAM. It's so just you guys know these particular hormones are used in males and females. But in this particular section, I'm going to specifically talk about how they're used in males to make sperm. Okay, so sperm a genesis, actually begins in puberty off the mail, and then it doesn't end until the males death. So it's going to go from puberty all the way through the rest of his particular life. Okay, and then we do have some important hormones that are utilized for this process. One of them is going to be called the Gonadotropin Releasing Hormone, or G N R H for short. And it's going to be a hormone that's going to be released by the hypothalamus. And it can also be called Just Do you guys know it is also called Oh no, also called Go Nod Oh Libera in Granada. Liberate those. They're going to be the same two hormones just generally, whenever we're talking about the natural hormone that's produced by human beings or other organisms, it's G N R. H. But whenever we're talking about the hormone that is made synthetically and that is a prescription drug, we're gonna be talking about Granada liberal. But they do the exact same thing, okay, and these were going to be created by the hypothalamus, and then they're going to travel to the pituitary gland, specifically the anterior pituitary glands, and this gonadotropin hormone is going to be made to actually turn other hormones on. So this is like a checklist. The gonadotropin hormone is made, it travels to the anterior pituitary, and then it's going to ensure that these L, h and F S H hormones are going to be generated as well. It's like flipping a bunch of switches. So what is the L H Hormone? The LH hormone is going to be the lutin izing hormone. And I'm gonna I'm kind of in the way of the definition, So I'm gonna out of the go out of the picture for a second. So this lieutenant, using hormone is going to stimulate these very interesting cells called Les dig cells. Laid egg cells are very important for male development because they're going to be very important because they create testosterone. So they're going to be found in the semen efforts tubules, where the sperm mermaid and these cells are going to ensure that testosterone is going to be made in the male organism. So testosterone is going to be the male sex hormone. And androgen is another word for a sex hormone or a male sex hormone, and it's going toe obviously help with sperm attic Genesis. And it's also going to help with many of the male characteristics that male organisms have that are specific to that particular organism. Now, Ludin izing hormone is going to work in conjunction with the follicle stimulating hormone. They're gonna work together. So the gonadotropin turns both of these hormones on and together they're going to create the process of sperm, a genesis and testosterone production. So the follicle stimulating hormone is going to stimulate these really interesting cells, which are really cool called Sarah totally cells. But you may have heard of them before. They're commonly also called nurse cells. Nurse cells. It says here that they help with sperm a genesis, but they actually do so much. They are gonna be cells that are found in the seminary Frist tubules that obviously helped build the sperm. That's how they go from sperm motives to spermatozoa. These subtly cells help them develop into mature sperm, and these cells are also going to control the amount of nutrients and hormones that these sperm are going to receive. And these cells can even repair DNA damage if they have thio to ensure that these gametes, um come out perfectly or as perfect as they can get, so that's really interesting. So now what we're going to talk about is how these processes control each other with this hormone called inhibit in inhibit in sounds a lot like the word inhibit. And that is the whole point, because in Hib in is going to actually inhibit the release of F S H or follicle stimulating hormone. So in heaven is going to be made by our nurse cells, and inhibits is given out inside of the male test is to turn the follicle stimulating hormone off. And basically what this is is this is a regulation checkpoint. So whenever the follicle stimulating hormone is stimulating the store totally cells, we know that sperm a genesis is happening. So what this or totally cells are going to do is now they're going to create inhibit, which is going to stop the production of F. S. H. And basically what this is is a control mechanism to ensure that the production of F. S H and the production of sperm and testosterone doesn't get out of hand. It's just a check system to ensure that it doesn't continue or go out of control that sperm, testosterone and all of these processes are going at a continuous even level. Okay, everyone. So that's all we have for this particular lesson on sperm. A genesis. And in our next next lesson, we're going to talk about gay media genesis, but specifically how you make eggs inside of a female. Okay, guys, let's go into our next lesson.

Gamini, Genesis and females is no Nas o Genesis, and this is gonna result in the production of an over. Um, now an ovum is a female gammy or an egg sale. And it's going to have these particular layers that you should be aware of on the outside the Corona radio otta, which is the outer layer that the sperm will actually have to penetrate to fertilize the egg and the zona pellucida, which is a layer of Gleicher proteins inside the Corona. And we'll get Thio What is going on during fertilization? Just a little bit now. O Genesis actually begins before birth. Remembers formatted Genesis doesn't happen till puberty. O Genesis O Genesis begins before birth but doesn't complete it. Actually arrests at a certain phase and then after puberty will continue. And this process actually stops after what's known as menopause. So oh, Genesis starts with Ogoni A these air female deployed germ cells that will divide by mitosis and actually begin my oh sis prior to birth. So they divide by my oath or mitosis and form primary oocytes that will start my oh sis, and then stop at pro phase one and each one of these primary oocytes is gonna be contained in a structure known as a follicle. This follicle is going thio not only contain the primary oocyte, but play a role in the menstrual cycle. And we'll talk about the menstrual cycle in more detail in just a moment, but very briefly each month. Basically, in humans, the cycles different other organisms. Each month, FSH follicle stimulating hormone is going to cause the follicle to mature. And it's going to cause the primary oocyte to complete my Asus one and then the resulting secondary oocyte will begin my Asus two. Now the follicle will rupture and release the ove Um and the remaining structure will form what's known as the Corpus Ludie. Um, this is a temporary endocrine structure that will release a lot of progesterone and some extra dial, but it will eventually go away and again. We'll talk more about that in just a moment when we talk about the menstrual cycle. Now, these secondary oocytes are gonna be cells arrested at meta phase two of my Asus two, and if they get fertilized by a sperm, they will actually then complete my Asus two and then form the complete excel and join with the sperm. Now, during the process of my Asus, these oocytes are going to form polar bodies. These air basically small hap Lloyd cells that result due toa unequal psychokinesis during O Genesis. Basically, each biotic division during this process is going to result in a polar body and that polar body doesn't develop into anything. So basically, unlike sperm, a genesis where these biotic divisions give rise to multiple cells that all will go on to become sperm in O Genesis Onley, one cell of the biotic Divisions is gonna go on to form the egg cell and you can see a model of that right here. However, I want to point out that Onley two polar bodies will form. Let me actually jump out of the way here. As you can see, the first polar body will form as the primary oocyte completes my Asus one forms the secondary oocyte. And when the secondary oocyte completes my Asus two, it will form a second polar body. Now with that, let's actually go ahead and flip the page and talk about menstrual cycle

The menstrual cycle is a regular cycle in the female reproductive system that can be divided between the ovarian cycle and the uterine cycle. The menstrual cycle will cease after a certain point in females lives known as menopause. Now the ovarian cycle is going to involve cyclic changes in the follicles of ovaries, whereas the uterine cycle is going to be the cyclic growing and shedding of the N Dmitry aligning. Now the ovarian cycle begins with the flick Euler phase. This is the part where the follicle matures and gets ready to release The ove Um FSH is going to stimulate follicle maturation, and the follicle will secrete extra denial. An important estrogen ovulation is the release of the ovum from the follicle, and it will travel into the fallopian tube. This occurs in the middle of the ovarian cycle, and it's triggered when maximal estradiol concentrations caused an L H spike and this L H Spike causes the follicle to rupture and release the of, um, aka population. Now the Louisville phase is the final part of the ovarian cycle, and this is where the follicle transforms into the Corpus ludie. Um, that temporary endocrine structure we mentioned the Corpus Ludie Um, is going to secrete progesterone, and this is going to maintain the uterine lining, and it's going to provide negative feedback toe FSH and LH. Now. The Corpus Ludie, um, will degrade if there is not pregnancy. If fertilization and implantation don't occur, we'll talk about what happens if they do occur a little later. Now. The uterine cycle, as we said, is going to involve the endometrial lining. The first part of the uterine cycle is actually menstruation. This is where the endometrium is shed, so that's occurring during the Filic Euler phase. Now the proliferation phases, the second part of the uterine cycle. This is where the endometrium actually grows, and you can see all of this happening in this nice chart right here. Now the final part of the uterine cycle is the secretary phase, where the uterus prepares for implantation. Basically, it gets ready for a fertilized egg to make its way there. Now it's worth noting that some organisms actually have what's known as an estrus cycle. During an estrus cycle, the uterus actually re absorbs the endometrium in the absence of pregnancy, rather than secrete ing or shedding the endometrial lining like we see in humans. And here you can see the various phases up top. We have our, uh, phases of the ovarian cycle. You can see the follicular phase, Lou deal phase and right here in the middle, that's ovulation. And notice how on this graph showing hormone levels, we have a new estrogen or we have estrogen reaching its peak rather right there. That triggers that L h Spike that we see. And that is what causes ovulation, where the ovum is released from the follicle. And here you can see and example of the shedding and the building up of the endometrial lining. All right with that, let's go ahead and flip the pain.

Hello, everyone. In this lesson, we are going to be talking about the process of fertilization or the creation of a zygote. Okay, so let's get into our lesson. And the process of fertilization commonly is also called conception. This is a very common term, especially for human beings. Now fertilization is going to be the formation of a zygote from the fusion of an egg and a sperm. And the way this is going to happen is the sperm is going to have to enter the female body, and then it's going to travel through the cervix, which, if you guys remember, is the opening to the uterus, and then it's going to travel into the ova duct. Now what are over? Duck specifically called in human beings in human females there, specifically called fallopian tubes. But they are also going to be called uterine tubes. These air both meaning the same thing. I just want you guys to know those terms as well. In case you are given those terms on a test, they mean the same thing. Fallopian tube, uterine tube over ducked all the same thing in a human being. Okay, And once the sperm enters the oval duct. There should be an egg there or an ove, um, and that is going to be fertilized by that sperm. Now, upon the sperm entering the of, um, it is going to complete my Asus two and then they are going to fuse their nuclei together to create a deployed nucleus or the zygotes nucleus. Okay, everyone. So this is going to be the process of fertilization, and it's not as easy as you may think. The sperm has to do a lot of work to actually fertilized this egg, and part of it is going to be because off the jelly coat that it has to fight through and all of these reactions, we're going to have to take place inside of the egg as well. So the first thing that the sperm is going to dio is is going to do sperm binding sperm binding is going to be the very first step of fertilization. And in this step, the sperm attache's to the jelly coat. So the jelly coat you guys can see is labeled here, and this is going to be this orange structure right here, that orange layer off the egg and this jelly coat is going to be made of glycoprotein, and it's gonna be this very thick, viscous structure that the sperm actually has to push its way through to even get to the plasma membrane of the egg. And this is gonna be a protective structure for the egg, and it's going to work. Thio eliminate a mass number of sperm actually getting to the egg because they have to do so much work to actually get to the eggs membrane. So sperm binding is going to happen in the sperm is going to attach to the jelly coat in mammals. The jelly coat is also called the Zona Pellucida. Okay, guys, just so you guys know, let me write that down for you. It's also called the Zona who lucida in mammals specifically. So in our eggs human eggs it's going to be called the Zona Pellucida, but jelly coats a little easier to say. So what's going to happen now is once the sperm actually bind the jelly coat, the Ark a zone or the ark is, um is actually going to open up. And the ark is, um is that cap on the end of the sperm or the head of the sperm, and it's going to open up and it's going to release these arcas own enzymes. So this is going to cause the arcas own reaction to begin the Ark Assam reaction is actually going to dissolve that jelly coat and allow the sperm to actually dig through the jelly coat and get to the plasma membrane of the sperm. So the next thing that's going to happen is the sperm membrane fuses with the egg membrane. So now that these membranes actually fuse, which you guys can see in this particular reaction right here now that these membranes air actually fused, they're actually going to stimulate another reaction toe happen. And that is gonna be the cortical reaction. And you guys can see all of these little structures thes little yellow circles here are gonna be cortical Granules, and they're waiting for a sperm to actually bind its plasma membrane with the eggs plasma membrane. And once it does that, it's going to begin this cortical reaction. As you guys can see, these yellow circles are actually diffusing into the membrane, and they're going to release cortical enzymes, which is actually going to change the chemistry off the membrane of the egg cell, and what this is going to do is it's going to ensure that no other sperm buying to this egg. So what is going to do is going to block Polly sperm E Polly sperm is going to be basically more than one sperm fertilizing one egg. And in most organisms, you don't want that because you have too much genetic material in that particular egg. Some organisms there are exceptions, but in US human beings we only want one sperm and one egg to come together because then you have the perfect amount of deployed genetic material. And you guys can see in this diagram here that the genetic material of the sperm is actually entering the egg. And then those two sets of genetic material refuse to make these zygotes genetic material. So that's a brief overview of how fertilization is going to happen. If you guys want more information about the details of the Ark is own reaction or the cortical reaction, and he talks about that whenever we talk about animal development. Okay, so let's go down and see what happens after the fertilization process has happened. What's gonna happen next? What's gonna happen next is the zygote is going to form, and it's going to start developing into the embryo into the fetus. Okay, so what's going to happen is this is thes. I go here, these I got is that first cell that is made by the fusion of the sperm and the egg, and it's gonna have two sets of chromosomes. But on the very first day, it's going to start dividing via the process called cleavage. Cleavage is a very specific type of division. It's not like most mitosis. Cleavage is where cells split without getting bigger, so they're going to say, Stay the same general size. And this is generally going to allow this dividing Zygo, this dividing embryo to move through the fallopian tube without being too big. So you guys can see the very second day cleavage is going to begin and make all of these particular types of cells. Now, do you guys know what this structure is called? Because it's no longer Caldas. I go. Once it starts having cleavage, this is going to be called a more Ula a memorial A is going to be a solid ball of cells. Now the Morial A is then going to undergo this process called compaction, and that's happening right here. And the cells are actually binding together via Desmond's OEMs and via tight junctions and their compacting together. And then they're going to undergo the process of differentiation where they become different cell types in the developing embryo, which will then develop into different tissue types and different organ types. But all of these steps right here are gonna be happening to the memorial. Uh, so in the first day, you're gonna have fertilization and the creation of a zygote. And then on the 2nd, 3rd and 4th day, sometimes the fifth day, you're going to have the production of the more ULA, and it is going to be developing and compacting and differentiating. And then, on the fifth or the sixth day, you're going to have the formation of the blast Ula. So this is going to be the blast, Sheila, and it's different from Memorial A because it's no longer solid. It's actually going to be, ah, hollow ball of cells. As you guys can see, it's gonna have this cavity, and this cavity is going to be called the blast. Oh, seal. And this is going to be a fluid filled cavity. And it can also be called the blast to see, like, cavity, as they call it here in this diagram. Now, this is a blast, Sheila. But whenever you're talking about a blast, Sheila that specifically found in mammals, this is going to be called a blast Assist. So this is specific to mammals. So our blast villas are called blast assists. Okay, but all organisms have blast jealous, okay? And this is a hollow ball of cells that forms from the cleavage of the zygote in the fallopian tube. And it's gonna have two types of cells I want you to know about. It's gonna have these inner cell mass or inner mast cells, and it's gonna have these trophoblastic cells. Now the inner mass cells or inner cell mass are going to become the fetus after they begin to divide and begin to form basically the baby. This is where the baby is going to come from, and then the trophoblastic cells are actually going to become the placenta and any other supportive tissue that is needed. So these trophoblastic cells they're going to be the ones that air here in this ring of cells. And then the inner cell mass are gonna be those cells that you see in red. So there are also different terms for this that I want you guys to know their different terms for the inner cell mass. They can also be called the Epi blast or the embryo blast. Hopefully, you guys can see that, um, the embryo blast. They're all the same thing. They're just different names for the same thing. So embryo blast. So these are all also the inner cell mass. They're the same thing now. The truffle blast generally only has that one name. Okay, All right. So that's going to be the basis of what's gonna happen in the first couple of days. So now what's gonna happen next is the process of implantation. And I really like this diagram here because it does show you where all of the processes that we just talked about actually occur. So you guys can see here. I'm highlighting in yellow. This is the ovary. This is where the egg is going to be made. And this is going to be where this follicle right here Reduce it are. Excuse me. The follicle actually produces the egg and releases it. So the oocyte is going to be the egg now. Actually, fertilization doesn't happen in the uterus. Most people think it happens in the uterus, but it doesn't. It's actually going to happen in the fallopian tube right here. We can see the sperm coming to bind with the egg, and then they are going to form the Zygo, which you guys see here. This one right here is showing that the two nuclei of the sperm and the egg er actually fusing together and then we're going to form the zygote. Now we're going to have the cleavage begin around, day to, and this is going to form the more ULA. And as the more Ula is dividing and it's differentiating and it's compacting, it is going to be traveling through the fallopian tube to the uterus. And then finally, in day 5678 and nine we're going to have the blast Ula actually implant into the wall of the uterus, which you guys can see right here. So this is the implantation off the blastocyst or the blast Sheila. And then this particular little mass of cells will begin to grow, begin to differentiate and form the entire fetus and the placenta as well. Okay, everyone. So that was our lesson on the process is off implantation and fertilization. Next, we're going to talk about child's birth and gestation.

pregnancy or gestation, as it's known, is when there's one or more embryos in the uterus. Now, pregnancy in humans is divided into trimesters, and during the first trimester there's a lot of interesting stuff happening following implantation. This hormone human chorionic gonadotropin hormone, or hcg, as it's often referred to, will be secreted and will actually prevent the degradation of the Corpus Ludie, Um, and halt the menstrual cycle. Interestingly, this hormone is actually what ah lot of pregnancy tests test for, and you can see an example of that right behind me. There. Now, the outer layer of the blast assist is known as the trophy blast, and this is what's going to grow into the endometrium to form the placenta. Now the placenta is an incredibly important organ. It's going to allow for the exchange of materials, nutrients and wastes between the mother and fetus. This is how the developing embryo is going thio, eat, breathe and get rid of its waste products. So very, very important. The developing fetus is connected to the placenta by umbilical cord, and this actually contains two arteries and a vein. Now the fetus is going thio or technically, the embryo is considered a fetus once it has its adult structures in their rudimentary form. And this is gonna happen through Organogenesis or the development of organs. And you can see here how the fetus is curled up inside the womb and how it has this bundle of two arteries in the vein that connects to the placenta. Now, in humans, we give birth to live offspring. This is known as or were known as vv Paris organisms for this reason, but some organisms lay eggs and this is known as over Paris. Whereas some reproductive strategies are Aviva Paris. This is when the egg will remain inside the parent until it's ready to hatch. No, With humans, we undergo labor these air uterine contractions that will expel the fetus from the uterus. And this is stimulated by the hormone oxytocin. And this is actually involved in a positive feedback loop because pressure from the head of the fetus on the cervix stimulates oxytocin, release oxytocin stimulates uterine contractions, which we're gonna increase the pressure on the cervix leading to more oxytocin release. So you can see how this is a positive feedback loop. Now we humans are considered the theory INS because we give birth to live developed offspring. There are other types of mammals, though no nas monitoring, which actually lay eggs and marsupials that give birth thio underdeveloped offspring that have to remain in this pouch that actually contains the mammary gland nipple. Now, mammary glands are what define mammals and or one of the things that defined mammals and these air going to be glands that secrete milk in a process known as lactation. The hormone proact and stimulates this milk production and oxytocin actually stimulates the secretion of milk in response to you suckling by the infant. That's all I have for this lesson. I'll see you guys next time.