Now, to fully understand what the system is and how the loop of Henley actually creates this concentration gradient between the surrounding tissue and the lumen of our loop of Henley, let's begin with our thick ascending loop of Henley. So we're essentially going to work backwards. Now, as I mentioned earlier, the thick ascending loop of Henley contains epithelial cells that are relatively thick, relatively large. It contains large, simple squamous epithelial cells. Now, if we take a small section of our thick ascending loop of Henley, we basically get the following diagram. So these are the large, simple squamous epithelial cells.