In this video I'm going to talk about the tissue layers in the bladder and show you what they look like at different magnifications and also show you how a bladder looks when it's contracted and empty versus when it's distended and full. The bladder has three different layers The innermost layer is the mucosa and just like all mucosas. It's made up of an epithelium and lamina propria So this thin layer up at the top is the epithelium and it is transitional epithelium.
The lamina propria is the much thicker layer right underneath it. So all together this is the mucosa. When the bladder is empty it kind of contracts and scrunches up so the mucosa is going to display these big ridges. And those ridges are called rugae, just like you saw in the stomach.
Underneath the mucosa is the muscularis layer, and the bladder, the muscle, is the detrusor muscle. So you could just say that this is the detrusor muscle. And right underneath the detrusor muscle, we can see... little bit of adventitia.
In the case of the bladder, the adventitia is just a loose connective tissue that's anchoring it to surrounding structures. Most of the bladder has adventitia, but the superior surface of the bladder actually has serosa. This is because the superior part of the bladder is kind of poking up into the abdomen, so it's being covered by the peritoneum. Remember the peritoneum is the serous membrane in the abdominal cavity. So any organs that are being covered by the peritoneum are going to have serosa instead of adventitia because the peritoneum is a serous membrane.
Now let's look at these layers a little bit closer. The transitional epithelium is special because it has the ability to stretch. So pay attention to the fact that the top of these cells have kind of a bubbly appearance because that's going to contrast with what we're going to see when we're looking at a full epithelium. distended bladder.
So underneath the epithelium is the lamina propria. As we go downward we can see the smooth muscle of the detrusor and then the very bottom there's that thin little bit of adventitia I was talking about. So before we look at the full distended bladder.
Let's look at those epithelium cells a little more closely. Now you can see much more clearly the transitional epithelium and that there's multiple layers of cells with a bubbly top. Moving on to the full distended bladder. Even on the highest magnification of 40x, we can still see all of the layers of the bladder because that's how much thinner it has become being full.
And most importantly, when you look at those transitions, epithelium you can see that the tops are now flattened out and it has kind of a concave appearance rather than the convex bubbles that you saw in the empty bladder. So regardless of how high the magnification is if you just look at the shape of the epithelial cells that'll tell you whether it's an empty bladder or a full bladder.