 So let's think about simple cuboidal epithelium. You know the term simple means that it's only one cell layer deep, and we've talked about cuboidal, meaning that we have cube shaped cells like a pair of dice, each one of those would be a cube. So I have a micro-scope slide of a kidney up, and the kidney of course has all sorts of little tubules that are involved with regulating the composition of the blood. And those tubules are made out of simple cuboidal epithelium. So I just want to point one out here. Now if you think about your arm as a tube, for example, if we made a cross section of that tube, then what we would see is essentially a circle. And since it's a tube, it has a hollow space called a lumen. There are pipes running through this building that are water pipes, and water runs through the lumen of those pipes. And so this would be one of the little tubules within the kidney. If we look at a cross section, it would be circular. And it's simple cuboidal epithelium that lines that particular tube. And so you can see the simple cuboidal cells that I've drawn here. We wanted to look at one cube shaped cell. We could draw it something like this with the oval nucleus sort of in the middle of the cube. I want to point out a structure here, which is also the lumen. And you can see it right there. This is a section of a tube that's running sort of longitudinally. When the microscope slide was made, it just so happened that the cut was running longitudinally to that particular tube. And you can see some of the cube shaped cells that make up this particular tube in the kidney. So each of these are simple cuboidal epithelial cells. Now if we look in this area, you adjust that focus just a little bit, you can see where we have more of a cross section of a tube. And so this is the tube, there's the lumen. And you can see, I'm not drawing over this very well, but you can see that would look something like that. Let me erase that. So simple cuboidal epithelium is made up of cube shaped cells. We find this tissue lining the ducts of glands and lining the tubules in the kidneys. A lot of exchange takes place in the kidneys of waste that are moving out of the blood and into what we call the filtrate. So that's simple cuboidal epithelium.