 The esophagus might be the easiest part of the tube to identify. Check out this slide. Do you see a lumen? I can't draw on this, but here is my lumen. Now, what are we going to expect to find next to the lumen? We're going to expect to find epithelial tissue first. And indeed, ready? You're in the esophagus. What kind of epithelium do you see here? What does that look like? It is quintessential stratified squamous epithelial tissue. Done. First things first, check the epithelium. If it's stratified squamous, you know you're in the esophagus. There are other options. There are other places where you will find stratified squamous epithelium in your digestive tract, but none that we're looking at. The esophagus is the only part of the tube that we're looking at that's lined in stratified squamous epithelium. So if you see it, you're done. You know that you're in the esophagus. Why? Why do we have stratified squamous epithelium in the esophagus? You're actually swallowing down giant blobs of partially masticated food. And so that, like, that's rough. That's hard on your body. Yeah, let's protect that tube as we're pushing food down it. Are we doing anything else in the esophagus other than pushing food down? No. So, you know, are we going to invest in things like microvilli? Why bother? Because we could throw some microvilli out here, but we're not doing any absorption because we're protecting the tube instead. Now, if you remember what stratified squamous epithelium looks like, this is actually my basolateral edge, my basement membrane for this epithelial tissue would be found right about here. Now, here's the interesting thing. Deep to that is going to be my laminopropria. Now, check out that. And then deep to that, look, there's smooth muscle. That, I mean, look at that. Doesn't it look kind of gloopy and gloopy? It looks smooth to me. It looks smooth and like my nuclei are kind of elongated. Doesn't it look like that? And check this out. Doesn't that look like a mess? That's your submucosa right there. If I were looking, I would guess, oh, it looks like my, this might actually be my muscularis mucosi right here. And this is my laminopropria. So, the muscularis mucosi in this one actually looks pretty thick. You're not always going to have it be that clear. I'm going to zoom out again to give you perspective of where we are. So, epithelial tissue, laminopropria, just deep to that. Muscularis mucosi in this case is pretty thick. And then we move into submucosa. And then who do we expect next? We expect muscle tissue. And this is muscularis externa. These big blobs of muscle, that's your muscle tissue right here. So, we have several layers of muscularis mucosi. And then we get out to the rest of the tissue, which actually we've got some trachea over here. Trachea actually has the same layers as the rest of your digestive system. It's just made of different things. I think that is helpful. Are there, is the epithelium stratified squamous? If it is, you're in the esophagus. Done.