There's a lot of magic that happens during animal development. I mean, it's incredible to think that a single cell this is I go will eventually become a complex body like that of an animal. And to think that the genetics of that zygote will determine how it forms, and those genes will control whether or not it forms into an elefant or fish. I mean, it's totally crazy. Um, of course, it's not magic, it's biology. And it's just amazing to think about the precision control that happens during development. So let's actually take a look at animal development. So of course, you start with single celled zygote, right? And that's going to go through cleavage, which are Siris of Rapid, my ta tick divisions that lead to a blast yola, which is a hollow ball of cells. You can see it right here. And, uh, these blue cells are the outer ring of cells, this yellow stuff that is representing the hollow space inside the blast villa, which is called a blast ical case. You're curious. And, uh, it's also worth noting that, um um alien blaster is called a blastocyst, just in case you hear that term come up. So then this blast Ula is gonna go through gassed relation which leads to the formation of a gas strolla. And basically, this is the formation of the three germ layers which are sort of these layers of cells that will develop into the complex tissues and features of the animal body. So, during gas relation, the blast July will imagine eight. It will create this cavity that we call the Arken Theron. This cavity in here and the opening to that cavity is called the blast of port. And the, uh this cavity will actually become the digestive too, which is pretty crazy. What's even crazier to me is that the blast support that opening in the gas strolla will actually become either the mouth or the anus of the organism. So this first opening in this what is literally just a cluster of cells will actually lead to a major orifice of the body. Now thes three germ layers. You can see here we have the ectodermal, which is the outer layer of, um, cells. And these are going to form nerves. Organs like the glands rather like the adrenal medulla, uh, skin the brain, the eyes, the inner ear thes air, of course. Human right. Mammalian examples. But just to put it in context, uh, that is easier to grasp. But the main point is that the ectodermal is the outer layer. The end of term is the in, er lair, and the end of term is going to give rise to stuff like the lining of the digestive tract, the liver, the pancreas and lungs. And it's actually not depicted in this image, but I'm gonna draw it in. There's also a middle layer that we call the Miso Durm and the me Zod, ERM against that middle layer and the me Zo Durham is gonna give rise thio organs like the adrenal cortex, the blood bones, the go nads and soft tissues. Now I said that blast support will either turn into the anise or the mouth and turns out that this is actually a pretty important distinction in biology. Which one it becomes now Here we have a nice little image of Hey, blast Ula going through gassed relation. Right. Here's our blast of port opening up and notice how this cavity will actually eventually go all the way through the organism I mean, you haven't opening it to ends its ah, common feature of animals. Sometimes, um, you know, your professor might joke that we're all just tubes, which is kind of true in many ways. You know, our bodies were set up to just be a Siris of tubes, and we have, of course, tubes running through our bodies that open at one end and the other now getting back to the blast report depending on whether that turns into the mouth of the famous, you're either considered a proto stone or due to a stone and a proto stone is an organism like the one we see right here that is going to have its blast report developed into the mouth. That's what's being depicted here. Mouth and the other opening will end up being the anus. Do tourist stones are the opposite, Uh, in do tourist owns the blast of port will actually develop into the anus, and it's the other opening that will become the mouth. And you can see an example of a Dutra stone right here. And you might also notice there's some other details about how the music term will form the Coolum and I don't want you to worry about that too much just yet. As we haven't talked about what a column is yet. I'm just putting that in there because technically, that is that also applies Thio the definition of protest. Um, and do her stone, and you can see that that's been, uh, labeled here. We have the museum tissue here and here, and it is turning. Uh, it is, uh, depending on whether your protest, Omar Judo stone doing different things to form the column, which is a type of body cavity. Now, it's really important to realize, given all this, that humans are actually do tourist stones. Which means at one point in everyone's life, you were just nothing but nastiness right there. Just kidding. All right, let's flip the page.
