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. Now, as we see on the diagram, the membrane of these cells contains specialized proteins that are responsible for using ATP molecules, energy molecules, to establish a gradient inside our interstituum, between the interstituum and the inside the lumen of our loop of Henley. So let's discuss how this is actually achieved. So, let's begin on the basil lateral side of our cell.