ELECTRON MICROSCOPY: URINARY: KIDNEY: RENAL MEDULLA, labeled; Scanning Electron Micrograph, RENAL MEDULLA. A = ASCENDING THICK LIMB, D = DESCENDING THICK LIMB, C = COLLECTING DUCTS, YELLOW ARROWS = CILIA, CYAN ARROW = CAPILLARY (VASA RECTA), T = THIN LOOP OF HENLE