These structures’ epithelium is the origin of the canine-derived MDCK cell line. Two portions of these non-intestine structures can be distinguished by the presence of brush border cells. Necrosis in these structures produces “muddy brown casts.” These structures are regulated by an apparatus composed of lacis (“LAY-siss”) cells, JG cells, and the macula densa. Filtration slits connect these structures to capillaries in foot processes controlled by podocytes. The MDRD and Cockcroft–Gault equations measure creatinine (“cree-AT-uh-neen”) clearance (10[1])through these structures. (-5[1])The cortical (10[1])and juxtamedullary types of these structures are distinguished based on the length of the loop of Henle, (10[1])and use (10[1])countercurrent (10[1])multiplication to concentrate urine. For 10 points, (10[1])name these functional units of the kidney. ■END■