 Let's talk about where sperm come from. Before we can talk about where sperm come from, we need some anatomy of the structure that's making the sperm, and that's the testis. Here is a little section of testi that we have sliced open and peeled stuff back. And so I want to label the parts while we're here because this is all required anatomy. And so probably we should start at the top with this structure that looks kind of like a cord because that's what it is. It's the spermatic cord, of course. The spermatic cord includes, that's how the testis receive blood, innervation, they drain their blood there, and the vas deferens, which is the sperm tube. The sperm highway. The vas deferens is also found in the spermatic cord. The vas deferens is shown here. The vas deferens is also called the ductus deferens. And you can see, I mean, take a second to look at the vas deferens. I'm pointing to it at the very top of this drawing, but notice that, oh, holy cow, like tubey wood madness of tube madness. All of these tubes basically feed into the vas deferens. And that's how our sperm, once we build them, are going to get out of here. I also want you to notice that there's this pinkish layer surrounding the spermatic cord, and that's a muscle. It's called the cremaster muscle. And this, oh, this is so cool. Despite popular knowledge, the testes weren't always on the outside of your body, fellas. At one point, okay, most people probably already know this, but at one point, your testes actually were up in your abdomen. And there's a structure called the gubernaculum. I love the gubernaculum. That actually pulls the testes through the abdominal cavity, through the peritoneal cavity, actually. The testes were in the peritoneal cavity. And this gubernaculum pulls the testes out through the inguinal canal and down into the scrotum. This process happens before boy babies even come out of their mamas. So, and it's dissension of the testes. And some boy babies, when they come out, if they didn't stay in long enough or there were some other kinds of issues, then the baby's testes haven't made it all the way out into the scrotum yet. But eventually, they get out. They started up inside the abdomen. When they come out, when they come through the inguinal canal, they, there are structures that they kind of like, it's like they get stuck to the testes along the way and get pulled out with the testes. And the cremaster muscle is actually pieces of internal oblique. Remember we had to learn the internal oblique? That was one of our deep abdominal muscles. And pieces of internal oblique pass out through the inguinal canal and into the, into the scrotum and continue to surround the testes and become the cremaster muscle. There's another structure that comes with the testes when they come through the inguinal canal and guess who that is? I gave you a little hint because I told you these guys were a, part of, they were actually in the peritoneal cavity. And so it's actually a leftover piece of the peritoneum, the serous membrane, peritoneum. We find it in the testes. So we actually, and it's of course not called peritoneum, but it's called tunica vaginalis. And take a deep breath and don't freak out about the fact that it's called the vaginalis. But that's actually, you have a visceral layer and a parietal layer of tunica vaginalis. And though that is leftover, like whatever, dragged through pieces of the peritoneal membrane. Since it is a serous membrane, it carries the same function. It's producing serous fluid between the visceral and parietal layers so that we don't have too much friction going on. We also have another tunica that is like kind of a thick, it's deep to tunica vaginalis, deep to the visceral layer of tunica vaginalis, like immediately deep to that. And it's kind of a thick structure surrounding the whole thing called tunica albuginia. We'll be able to see that in our slides. Now all of that is surrounding these like tubi-looking structures right here. Oh, in fact, look, here's where I have a little box surrounding these guys and I blew it up somewhere else, but I don't have that picture with me right now. These are the seminiferous tubules. And just like you would think, I had a crazy net yarn knot of swirling, twirling tubes. This is where sperm production takes place. So within the seminiferous tubules, and I'm going to draw you a blown-up seminiferous tubule here so that you can see how the sperm actually get formed. Okay. Is that all of our anatomy? One more piece of anatomy, two more pieces of anatomy, three more things that I have labeled here. The seminiferous tubules are producing sperm and they look at how the seminiferous tubules all kind of converge on these tubes, ducts, or perhaps shall we say efferent ductuels. Perhaps we shall say it like that. The seminiferous tubules, the sperm that are built in the seminiferous tubules travel through the efferent ductuels in order to reach the structure that this like moon-shaped structure sitting on top of the testis. This is the epididymis, epididymis. And epididymis sits on top. The epididymis is where our sperm learn how to swim. It's a very important place. And then epididymis feeds into the vast efferents when necessary, when sperm are needed somewhere, which has absolutely nothing to do with the process of producing our sperm. So look, I'm going to draw you a giant blown-up seminiferous tubule. I'm going to draw a cross-section of one of them. Okay. So what is this again? It's a seminiferous tubule. And I could have made a cross-section of any of these guys. Every seminiferous tubule has a lumen. So I'm going to draw the lumen in the middle. And then how do we get sperm? Like, what? Sperm, sperm. How do we get them? What's the process? Well, we have to go through meiosis. If you are like myo-huh, like that, then I highly recommend that you go learn meiosis first. And I've got lectures on meiosis, and I'll send them to you if you would like them. But you need to have a solid, a relatively solid understanding of meiosis to have any idea of what I'm talking about here. Are you ready? We have cells along the basolateral edge of the seminiferous tubule. And these cells, they look really unconvincing. Like, who are these guys? They're kind of boring. And I'm going to label them with the number one. And I'm going to come down here and label them because I'm going to run out of room. These guys are called spermatogonia. Spermatogonia. So spermatogonia are these most basolateral cells in the seminiferous tubules. I'm going to tell you a little something, something about them. They're diploid. And they go through the process of mitosis. So they go through mitosis. And remember, back to your brilliant bio one days, mitosis is a process of nuclear division that results in two identical daughter cells. So the spermatogonia go through mitosis to produce two. This is going to be number two in my list here. They produce two primary spermatocytes. It's important to recognize we went through mitosis. So these guys are also haploid. I mean, I didn't mean that. I meant they're diploid because they've just their identical copies of the spermatogonia. The primary spermatocytes, okay, I think technically one of them becomes another spermatogonium and one of them becomes a spermatocyte. And one of my daughter cells just stays in this zone and becomes another spermatogonium, just maintains the original population. But one of them becomes a primary spermatocyte. So one of them is going to take like the next step in. And my primary spermatocyte is who is going to start going through mitosis. And if you remember, mitosis, the first division in mitosis, that's the reduction division where we reduce the number of chromosomes that we have. And you already know all this. So our primary spermatocyte begins the process of mitosis and results in secondary spermatocytes. You get two of them. And these guys are haploid. And so now this guy, that guy is going to give rise to two primary spermatocytes. Look, I need to make the colors a little bit different. What do you think? We'll make the primary spermatocyte light blue. How's that? And really I just drew this guy. I'm going to make that guy red, back to red again because it was just replacing the original one who divided it. Our secondary spermatocytes, if you remember from the process of mitosis, your secondary spermatocytes are haploid, but they have too much DNA. Awesome, that's just a defense for why we have to go through a second layer of my mitosis. And so let's do that. Each one of my secondary spermatocytes goes through mitosis too. And now we have spermatids. And these guys are not yet sperm. However, they're ready to be sperm. These guys are also haploid, so they only have one copy. And you'll notice that they're almost to the lumen of the seminiferous tubule. But why aren't they sperm? Take a look at those guys. Con, be a sperm. But why aren't they sperm? Because they do not yet have tails. So when these guys, this cell, my spermatid, is going to get a tail. So as soon as they get their tail, so this means plus a tail, as soon as they grow their tails, now what are they? Now they're sperm. Unfortunately, they're sperm who can't swim. They have to pass to the epididymis and have some thing happen in the epididymis. And that would be an awesome thing to research, but I don't know how that works yet. Somehow the epididymis goes and teaches these guys how to swim. It takes them like two weeks to learn how to swim in the epididymis. And then once they have learned how to swim, now they're functional grown-up sperm. Now they can be ejaculated and go do their thing and hopefully make some bivis. Did I tell you everything you need to know? Let me just highlight something here because you know it's fun. Pneumatosis was that first process. And then I wanted to make sure that you see that this right here is meiosis one and this right here is meiosis two. And that probably was a terrible color to pick, but you know what I was saying. All right. If that is how we make spermorama, then let's see how we make egzorama.