So the renal cortex is simply the outer portion of our kidney. Now if we zoom in on the distal convoluted tubule, we basically get the following diagram. So this is a cross section of our distal convoluted tubule. So this inside portion, the cavity is the lumen of our distal convolute tubule. Everything outside the distal convolute tubule is our surrounding tissue, also known as the interstituel. And these are the cells that are found that line the distal convolute tubule.