Now, by the way, because we essentially increase the concentration of our interstituum found in the mid dull of the kidney. What that means is we increase the hemotic pressure in the interstituum, and we'll see why that's important in just a moment. So let's move on to our descending loop of Henley, which is this section here. Now, at the top of our descending loop of Henley, the inside filtrate is isotonic with respect to our interstituent. Now, what exactly will happen as the filter travels downward? Now, the epithelial cells of the descending loop of Henley are permeable to water.