Transcription
Hi ninja nerds. In this video today, we're going to be talking about the development of the reproductive system. Before we get started, though, please continue to support us by hitting that like button, commenting down in the comment section, and please subscribe, subscribe.
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All right, ninjas. When we talk about the development of the reproductive system, we have to remember from what germ layer this actual reproductive system develops. You guys remember it's the mesoderm. But let's even be more specific. If you guys remember from the mesoderm, there were three different parts of it, right? The one closest to the neural tube was called the paraxial mesoderm. Then you had the one next to what's called the intermediate mesoderm. And then you had these two layers that splayed out, that was the lateral plate mesoderm. Right? And the part of the lateral plate mesoderm that was closest to the gut tube was called the splanchnic layer of the lateral plate mesoderm. And the layer of the lateral plate that was going with the ectoderm was called the somatic layer of the lateral plate mesoderm. Which one of these layers gives rise to the reproductive system? Do you guys remember? It's the intermediate mesoderm. That's the one that we need to focus on. So again, the primary one here that I want us to talk about is the intermediate mesoderm.
Now, what happens with this intermediate mesoderm? So the next thing you guys need to remember is that the intermediate mesoderm starts condensing. And as it condenses, it forms a specialized structure here called the urogenital ridge. The urogenital ridge, what you guys need to remember is that the urogenital ridge is what gives rise to the reproductive system. Particular parts of the reproductive system, though. It's going to give rise to the gonads. And you know, gonads looking to get, you can actually have either give rise to the male gonads, which will be the testes, or the female, which would be the ovaries. The second thing that you guys need to remember is that it also can give rise to the ductal system. And there's two ductal systems for, uh, the developing embryo. We'll talk about that. So the ductal system, okay, that's very important to remember.
Now, the next thing that you have to realize is that when we talk about the urogenital ridge, it is a core of mesoderm. There's a little bit of epithelial tissue around it. But what happens is that you guys remember your embryology, this is actually your gut tube, right? This is your gut tube. A better view of the gut tube is in a sagittal section. Let's take a look at the sagittal section. This is, there's a reason why I'm trying to mention this. If you take a look at the sagittal section, this right here, this entire green tube is your gut tube. And you have different portions of the gut tube, correct? You have the foregut, the midgut, and the hindgut. And at the bottom portion of that hindgut, what is this portion here that's close with the ectoderm? That's called the cloaca. We'll talk about that portion in a second because that also gives rise to a part of the reproductive system.
But what I want you to remember is here's your yolk sac, okay? This is your yolk sac. Your yolk sac has very particular types of special cells called primordial germ cells. And these primordial germ cells will migrate from the yolk sac towards this duct. What is this duct? This is called your vitelline duct. So from the yolk sac, these primordial germ cells will move towards the gut tube and then start infiltrating around this red structure. What is this red structure here called? We already talked about it. This red structure here, just in a sagittal view, is the urogenital ridge. And that's going to give rise to the gonads and the ductal system.
The next thing I want you to know is that these primordial germ cells, they love to infiltrate into the gonads. That's very important. So what I want to add on here is that from this actual urogenital ridge, the primordial germ cells from the yolk sac will infiltrate into it. And these primordial germ cells will give rise to the gametes. So this will give rise to sperm for the male gonads, and it will give rise to the oocytes for the female gonads. That's very important.
The last part that I want to talk about that's going to be important for the development of the reproductive system is the cloaca. You know, the cloaca gives rise to two structures. It gives rise to the anal canal, which is going to be posterior. There's a posterior portion of the cloaca. You get like a little septum called the urectal septum. It separates that cloaca into two parts: a posterior anal canal, and the more important one, prevalent to this actual discussion, is the urogenital sinus. And this is going to be the anterior division of the cloaca. This is what gives rise to a part of the external genitalia. So this will give rise to parts of the external genitalia.
So now that we understand how we actually kind of start developing our primitive reproductive system, we've got to start going over more detail and talking about, okay, we understand the primitive gonadal system, the primitive ductal, primordial germ cells, all that stuff. Let's talk about how they differentiate and become specialized towards male and female. Let's do that now.
Okay, so now we understand how the intermediate mesoderm gives rise to parts of the reproductive system and how the cloaca, which is at the end part of the hindgut, how that's going to give rise to other parts of the reproductive system, primarily the external genitalia. Let's kind of annotate, though, a diagram. Very important diagram, very important for us. Embryology step one that you have to understand the primitive reproductive system. What is these structures here? So let's talk about these. The first primitive structure here is these red structures. These are going to be the gonads. This is, this is the first one, okay? Now, they're gonads because we don't know yet if they're going to become male or female.
The next one that are on the sides of the gonads is one of those ductal systems. Remember we said that we'll actually develop ductal systems from that urogenital ridge. These here in blue are called the mesonephric ducts. There's another name for these, okay? And they're also called the Wolffian ducts. Also called the Wolffian ducts.
The next ducts, which are also on the sides of the gonads, are these like royal blue or baby blue ones. And these are called the paramesonephric ducts. So para means on the side of the mesonephric duct. So para, paramesonephric ducts, also referred to as the Müllerian ducts.
The last one here, this is, I honestly know it sounds like a made-up name, but it's real. It's this brown structure, which is actually going to be on the sides of the actual ductal system as well and the gonads. And this brown structure here is called the gubernaculum. So you have the gubernaculum, which is these kind of like brown structures on the side.
The last thing here is, as you kind of follow these mesonephric ducts and the paramesonephric ducts down, they empty into this structure here, this green structure, which we talked about came from the cloaca. It's the anterior division. Guess what this structure is? This is the urogenital sinus. Urogenital sinus.
So now what we have here is we have kind of the beginning parts of our reproductive system. Now that we understand this, what I need us to do then is talk about what steps do we have to go through chemically and cellularly to convert the gonads into ovaries or testes, the mesonephric ducts into the male ejaculatory system, the paramesonephric ducts into the female ductal system, and then talk about the urogenital sinus and talk about the gubernaculum and what function it has.
All right, so the first thing we have to talk about is how do the gonads know to lead to the male or female type of sexual gonads? Let's talk about that first. Okay, so the first thing that I want us to do is understand the differentiation of the gonads. That's the first part. So let's say we take the gonads. We're going to start with how the gonads become the testes or how it becomes the ovaries. That's the first goal. Well, the first thing you need to realize is that the changes in the gonad, the structure within the mesoderm, the changes occur when it comes to the male. So let's put XY. And the changes in the female, XX, occurs in different parts of the actual gonadal structure. The changes in the male, what will become the male testes, is going to occur first in the medulla of the gonad, okay? That's the first thing that I need to remember. The changes will start occurring first in the medulla of the gonads. For the female, the future female gonads, this is going to occur in the cortex, the edge of the gonad structure. So again, the changes that are going to occur in the gonads that occur in the medulla are for the male, will become male. And the ones that occur in the cortex of the gonad will occur for the female. What do I mean by this? Just that we're completely understanding this because I want you guys to be confused here. Imagine we take that gonad here, right? The changes that are occurring here in the center, that's the medulla of the gonad. The changes that are occurring around the edge are the cortical region. That's going to be for the female gonads, okay?
So now we understand that. Let's talk about how we actually start leading to this differentiation. There's a special gene, and this gene is called the SRY gene. Let's write that down. This gene here that actually starts being expressed on the XY chromosome, particularly the Y chromosome, is called the SRY gene, okay? Very important gene. Why? Because the SRY gene is going to lead to the expression of a particular type of molecule called testes-determining factor. And testes-determining factor is what gives rise to testes. So let's kind of follow that down. Then, if we take here, understanding that the XY, which was particularly for the male, they have the Y chromosome. The Y chromosome expresses the SRY gene. If they are SRY positive, what will they produce? They'll produce testes-determining factor. What will testes-determining factor do? It'll convert the primitive gonad into testes. But that leads to the next question: What are the testes actually made up of? That's the next important question we have to answer.
So let's talk about that. When you actually take a look at the testes and look at the microscopic structure of it, the testes are made up of a couple different things. One is they're actually made up of a lot of tubules, little tubules inside of them, kind of a little tubules that are all kind of like thrown throughout the entire structure. These tubules kind of come in different names. One is it's called the seminiferous tubules. Another one is called the rete testis. And there's another one too, called like the straight tubule. But again, these are the two main ones.
The next structure that comes from the testes that is very important here is going to be called your Leydig cells. Very important cells. Leydig cells. The reason why your Leydig cells are important is they produce a very important hormone called testosterone. Very important.
The next thing that actually is going to be within the testes is some other special cells called Sertoli cells. And Sertoli cells produce a very important hormone called Müllerian inhibiting factor. And we'll talk about what that is. And we'll abbreviate this. The Müllerian inhibiting factor, it can also be called the Müllerian inhibiting hormone. But Müllerian inhibiting factor.
Now we understand that this is what the testes are made up of for the most part. There's one other component, though. This was primarily coming from that epithelium and mesoderm core. But remember, we had those primordial germ cells that were coming from the yolk sac. Remember what I told you those primordial germ cells do? The primordial germ cells infiltrate into the testes in this case. And those primordial germ cells will give rise to sperm. So the sperm will also be a component of the testes. But that's going to be coming from the primordial germ cells.
So now we understand this. Okay, let's move on to the next part. Now that we know that the testes are actually formed due to the presence of the testes-determining factor, what's the next thing that happens? Well, we formed all these different components, but the really, the only two components that we're really worried about here is the Leydig cells, okay, that produce what hormone? Testosterone. So now the testes will start producing testosterone. That's one thing. The other hormone that's going to be produced here is going to be Müllerian inhibiting hormone or Müllerian inhibiting factor. So Müllerian inhibiting factor. What will these two things do? I'm glad you asked. Testosterone will then stimulate some very important pathways. You know, there's that ductal system we talked about, the mesonephric ducts. It'll help to stimulate the mesonephric ducts to continue to grow, to maintain their structure. That's the first thing. So it'll stimulate the growth of the mesonephric ducts. That's important. Why? The mesonephric ducts are what? Another name for them? The Wolffian ducts. Will give rise to what structures? Do you guys know? It's going to give rise to that male ductal system. What connects to the testes? You have your epididymis. What else do you have? Your vas deferens. What else do you have? Well, the vas deferens comes down and gives off a little like gland called the seminal vesicles. Seminal vesicles. And the last part is where it kind of moves through the prostate gland, it empties into the prostatic urethra. What's that duct called? The common ejaculatory duct. Common ejaculatory duct.
So when the SRY gene is activated, it releases testes-determining factor, generates testes. Testes produce testosterone. Testosterone maintains the growth of the mesonephric ducts. What will the mesonephric ducts continue to grow into throughout the embryonic development? The ductal system, primarily made up of epididymis, vas deferens, seminal vesicles, common ejaculatory duct.
All right, here's the next thing. You know, the female ductal system, we don't want that to grow. If a male, if you're going to become a male, you don't want to have the female ductal system growing at the same time. You don't want to have epididymis and vas deferens and have a fallopian tube and a uterus. So because of that, guess what the Müllerian inhibiting factor does? The Müllerian inhibiting factor inhibits the paramesonephric ducts, or what's another name for them? The Müllerian ducts. So it's going to inhibit the growth of the Müllerian ducts. What does the Müllerian ducts give rise to? Well, I already kind of told you, right? One is the fallopian tubes. That's going to give rise to the fallopian tubes. If you're becoming a male, you don't want to have fallopian tubes. It's going to give rise to the uterus. You know, you have the fundus, the body, the cervix of the uterus. And it's going to give rise to the upper two-thirds of the vagina. You don't want to have a vag if you're going to be a male as well. So the Müllerian inhibiting factor will inhibit the formation of the Müllerian ducts, which will inhibit the formation of the actual female ductal system.
What's the next thing? All right, testosterone. There's one more thing that we have to talk about. We've talked about how the testes are developed from the gonads. We talked about the male ductal system, how it develops, and how we inhibit the female ductal system. But we didn't talk about the external genitalia. We'll get into more detail of it later. But what I want you to know is that testosterone also gets acted on by a particular enzyme called 5-alpha reductase. And what this enzyme does is it converts testosterone into dihydrotestosterone. And you know what dihydrotestosterone does? It stimulates the development of the male external genitalia. So it's going to stimulate the male genitalia. And again, we'll go over that in more detail a little bit later.
So we understand how we develop the male stuff now. Actually, that we've done that, the female development of the reproductive system is actually very easy. Now watch this. So we need the SRY gene on the Y chromosome. Well, guess what? The female does not have the Y chromosome. So she's going to be SRY negative. If that's the case, then she does not express, there's no testes-determining factor. That means that this will not give rise to testes. As a result, by default, it'll give way to ovaries. Now, this begs the question: What are the ovaries made up of? You know what ovaries are made up of. It's actually much easier, thank goodness. There's two particular kinds of cellular components. Let's actually mark them over here. So the first one is, you have those epithelial cells and the mesoderm that are part of that urogenital ridge of the gonad. What happens is they become particular structures called follicular cells. These follicular cells are very special. You want to know why? The follicular cells are what produces estrogen and another one called progesterone. But particularly pertinent to this lecture is estrogen. That's the first thing. The second thing, which we're going to switch the colors that were consistent here, remember those primordial germ cells that came from the yolk sac, infiltrated the gonad? What did that become? It became sperm for males, but it also becomes oocytes for females. So that's another important thing because this whenever it combines with the sperm will give way to the ovum, the fertilized ovum. So that's the next thing.
So now we understand the actual activity of the ovaries. Now, the ovaries, whenever these are formed, they're going to produce estrogen. Guess what estrogen is going to do? Well, the first thing is that the estrogen, in particularly in the form of what's called estradiol, we really want to be specific, it stimulates the formation of the female genitalia. And again, we'll go over that in a little bit more detail later. So it's going to stimulate the formation of the female genitalia.
So so far, we have the development of the female genitalia due to estrogen. We have development of ovaries due to the lack of SRY gene. But what about that female ductal system? Well, follow along with me for a second. Come back over here, and we're going to change the color here for a second. Let's just do it in red. If the actual female is forming, there's no SRY gene, no testes that are forming. So because of that, no testes-determining factor. That means that you're going to develop no testes, correct? If there's no testes, you don't form what type of molecules? I mean, what types of cells? The Leydig cells, which form testosterone. So testosterone isn't going to stimulate the formation of the mesonephric ducts, and it's not going to be able to form male external genitalia by getting converted into DHT. So that process is gone. But more important than that, the other component of the testes was the Müllerian inhibiting hormone or Müllerian inhibiting factor. It was released by the Sertoli cells. Well, if you have no testes, you have no Sertoli cells. No Sertoli cells means that there's what? Means that there's no Müllerian inhibiting factor. If there's no Müllerian inhibiting factor because there's no Sertoli cells, what happens then? You're no longer able to inhibit the formation of the Müllerian ducts. Now, the Müllerian duct formation will be disinhibited, and you'll be able to stimulate the formation of the Müllerian ducts, or what's another name for them? The paramesonephric ducts. If you stimulate the formation of that, that'll give rise to the fallopian tubes. That'll give rise to the uterus. And that'll give rise to the upper two-thirds of the vagina. Boom! We've formed the female reproductive system up to this point, with the exception that we haven't talked too much about the genitalia yet, but upper two-thirds of the vagina. Okay, boom, we covered a big chunk there.
So now that we've done that, let's talk about one last thing, and that is the gubernaculum. That's the one thing that we didn't talk about yet. The function of this is actually pretty darn cool, not to mention it also has like a pretty cool name as well. The gubernaculum has different functions within the male and within the female, obviously, right? But the concept of how it performs these things is the same. The whole function of the gubernaculum is to guide the descent of the male or the female reproductive system down into the pelvic region. Because when your gonads are developing, they're actually developing at the abdominal cavity. So what the gubernaculum does is it guides descent of the testes right into the pelvic cavity. But particularly, there's a little structure called the processus vaginalis, and then you develop a little, a little tube later on in life called the inguinal canal, that pushes these actual structures, the testes, down into the scrotum. So it guides the descent to the testes from the abdominal cavity into the scrotum. That's important because once it's guided down into the scrotum, what happens is you're going to pull down. The gubernaculum will pull down the testes, it'll pull down the male ductal system, and it'll pull the blood vessels that are going to the testes. What is that whole structure if it's kind of circled around? It's called the spermatic cord. So the gubernaculum helps to guide the testes and the entire reproductive system of the male down into the scrotum to help with the formation of the spermatic cord.
So the gubernaculum within the female, it guides the ovaries, it guides the fallopian tubes, the uterus, all that stuff down into the pelvic cavity. So again, it guides the ovaries and the entire kind of reproductive system, the ovaries and the ductal system into the pelvis. But as it does this, what happens is the gubernaculum kind of splits into two portions, two little portions. And when it does, it forms two ligaments with that are actually very important around the uterus. One ligament that it forms is called the ovarian ligament. And the ovarian ligament is going to be between the ovary and the uterus. So that's one of the ligaments that the gubernaculum gives rise to. The other one, again, what happens is the gubernaculum connects up near the gonad, near the ovary. But as it does that, it clicks into the side of the uterus. And then the, the bottom part of the gubernaculum here will connect to the labia. So what happens is the bottom part of the gubernaculum connects from the uterus to the labia. And that's called the...
Now that we understand how we've formed for the most part, the formation of the male and female gonads, and we've also discussed their ductal system, and we talked about how we guided their descent from the abdominal cavity to the pelvic cavity, we now can identify the differences in an anatomical diagram. So now that we kind of have a very good understanding of how we develop and differentiate the gonads into male and female gonads, the ductal system into the male and female ductal system, and how the gubernaculum kind of guides the descent down, let's kind of identify these structures. That's very important here. So let's say on this side, this is going to be what happens to the male differentiation. And over here, this will be the result of the differentiation to the female sex.
So what will the gonad become here? It'll become the testes. Then the next part is what does the, uh, particularly the ductal system for males become? This would become the mesonephric or the Wolffian ducts. And what does that give rise to? A nice little quick, quick recap: epididymis, vas deferens, seminal vesicles, and then the common ejaculatory duct. The next thing here, now that we've understood that, is that the gubernaculum again, it'll pull this entire structure downwards and into the scrotum.
For the female, what does the gonad become? This will give rise to the ovaries. Okay, this will give rise to the ovaries. And then this blue structure here that's connecting with the ovaries, because again, what happened? The mesonephric duct got degraded for them. The mesonephric duct got degraded for the females. And all that's remaining is the paramesonephric duct. So this is the paramesonephric duct. And again, this is also referred to as what other name is this? This is also called the Müllerian duct. And again, what does the Müllerian duct give rise to? It gives rise to the fallopian tubes, the uterus, and the upper two-thirds of the vagina. And then again, the gubernaculum will pull this kind of whole structure downwards into the pelvic cavity, as well as giving rise to those particular ligaments.
The next thing that you guys need to remember is, we kind of, you see how there's a change in the structure. Remember the urogenital sinus? We talked about that one a little bit here. The urogenital sinus gives rise to a particular structure that we'll talk about more in detail over here. But with respect to this structure here, the urogenital sinus connects and gives rise to particularly the bladder. In this diagram, it also gives rise to a part of the urethra. It also gives rise to a part of the urethra. And again, to kind of correlate with this, remember we said that for the male, they have a common ejaculatory duct. That right there is the common ejaculatory duct. Look where it's emptying, right into the prostatic urethra region. So that's why that's important.
Okay, so we have an understanding of how we form the male and female reproductive system for the most part. Let's finish up talking about the development of the external genitalia.
All right, so we've, we've got to finish up talking about the development of the external genitalia because again, this is a very important component of the reproductive system. So a generalized diagram of a primitive kind of, uh, external genitalia, not specific to male, not specific to female. This is just kind of how it starts off. So if you look at kind of the base of, like, the bottom of the embryo where the genitalia are going to start developing, you kind of notice there's, uh, if you were to imagine here, you can't see the urogenital sinus, but if you kind of imagine here, I'll draw it in green, it would be inside of this kind of structure here. And again, we'll talk about what that is, but again, you can't really see that portion of the urogenital sinus. It's better seen in the sagittal section.
So here we're kind of looking at the genitalia. When we look at it, there's complete identifiable structures. The first one here is this brown structure. And this brown structure is called the genital tubercle. It's called the genital tubercle. That's the first thing that you guys need to know. That's the first structure that you need to know. It's kind of on the top part. On the sides, in pink, these are called your labial scrotal swellings. So labia, labial scrotal swellings. That's the next important part. Then in blue, right here, this portion here, this is called the urethral folds. So again, what are these called? These are called urethral folds. And again, it's important to realize you can't really see the urogenital sinus in this diagram. But if we took a sagittal section of the embryo, it's better seen here. So here's our sagittal section. We're kind of looking at a sagittal view here. And what you see here is, you can even see a small little piece here of the genital tubercle. So you can still see a piece of that genital tubercle here. But what is important is you have this green structure here. Again, this goes back to that diagram that you have to remember. There was a very particular structure, kind of dilated structure where the hindgut emptied into and where the mesonephric duct empties into, or the, you know, the mesonephric duct empties into, and that was called the cloaca. Remember the cloaca splits. And when it splits, it splits by this structure called the, what is this structure called? This is called the urorectal septum. And that separates the cloaca, which is this whole structure, into two parts. This portion here, which I'm going to kind of like break apart now, this portion here, which is going to be the anal canal, which is going to be the posterior portion. And then this portion here, anteriorly, this is going to be the urogenital sinus. And what happens is, remember that mesonephric duct? That mesonephric duct is coming down here and it's going to empty into that urogenital sinus. Remember it empties in near the urethra. That was the important thing to take away from that. That was the important thing to take away.
Well, what you need to remember is that this urogenital sinus, it's going to be this whole portion here. We're going to kind of outline it in blue. We're going to say it's from here to here, that's the urogenital sinus. And this last structure here, from the top, from this blue line to this point here, this structure here is called the allantois. Okay? So we have, I've been able to identify from these anatomical diagrams the main components that are going to give rise to the external genitalia. What are those main components that we need to focus on? It is the genital tubercle, the labial scrotal swellings, the urogenital sinus, and the urethral folds. These are the primary primitive external genitalia that we need to know.
Then what we need to understand is how these structures become either male genitalia or female genitalia. We kind of know a little bit about this. The first thing that I need you guys to remember, if it's going to become male, what hormone was guiding this process? Do you guys remember? Remember we had testosterone, and the testosterone was getting converted. Remember we had testosterone, and there was an enzyme called 5-alpha reductase, and that was converting testosterone into dihydrotestosterone. That dihydrotestosterone is what's stimulating each of these steps and trying to push these primitive structures into forming male genitalia. For the female, do you guys remember what hormone was guiding the development of the external genitalia for the female? This was estrogen, released by those follicular cells or the granulosa cells. That's going to be trying to stimulate the guidance of these primitive genitalia structures into making female genitalia.
Okay, now enough of that. Let's know what the heck the genital tubercle becomes in the male and in the female. In the male, this gives rise to what's called the glans penis. It also gives rise to very important ejaculatory type of tissue or erectile tissue, and that is called the corpus spongiosum and the corpus cavernosum. These are very important structures that you need to remember. For the female, the genital tubercle will give rise to the clitoris and the vestibular bulbs. Vestibular bulbs. Okay, beautiful.
The labial scrotal swellings, if stimulated, this is actually pretty easy, thank goodness. Labia scrotal, what do you think is going to become if it's for the male? The scrotum. So this will become the scrotum. And for the female, this would become the labia majora. Labia majora. All right, sweet. Pretty straightforward there.
The next one, a little bit more difficult, not too crazy with respect to the reproductive system, the external genitalia, and the presence of testosterone, the urogenital sinus will give rise to what particular structures? It'll give rise to the, the prostatic urethra. So, you know, you have the different parts of the urethra, right? The prostatic urethra. It's also going to give rise to the what's called the membranous urethra. And here's the important part here. There's also glands, okay, that are going to be around the prostatic urethra and glands that are going to be around the membranous urethra. There's a gland that is going to be around the prostatic urethra. What do you think that's called? It's called the prostate gland. So it's also going to give rise to the prostate gland in the presence of DHT. And then the membranous urethra is going to give rise to what's called the Cowper's glands. They're also called the bulbourethral glands. So that's going to be for the urogenital sinus. In males and females, it's pretty straightforward. It's going to give way to, they don't have multiple urethras, so it's just going to give rise to the female urethra and another thing which is called the, uh, the paraurethral glands. So the paraurethral glands. And there's also a little other glands called Bartholin's glands. So other small little glands around the area called Bartholin's glands. So that's going to be what the urogenital sinus gives rise to. Now, again, it's important to remember that it's for the urinary system, it also gives rise to the bladder. But again, we're talking about reproductive.
For the urethral folds, for the male, it's primarily going to give rise to the shaft of the penis. So it's going to give rise to the shaft of the penis, or pretty much the body of it, as well as there's a particular urethra that runs through the shaft of the penis, the primary body of it, and that is the penile urethra. All right, beautiful.
Last but not least, the urethral folds for the female, this is going to give rise to the labia minora. So this would give rise to the labia minora. And that will cover the development of the female and male external genitalia, as well as complete our understanding of the development of the reproductive system.
All right, engineers, in this video today, we talked about the development of the reproductive system. I really hope that it helped and I really hope it made sense. All right, engineers, thank you. Love you. And as always, until next time. [Music]