Although both have simple squamous epithelia, vasa rectae (v), which contain RBCs, are easy to distinguish from the thin limbs of Henle’s loop (HA10, T), which contain filtrate. As you move toward the apex of the renal pyramid, the epithelial cells of the collecting ducts get taller. In the inner medulla, close to the renal papilla, only vasa rectae, thin limbs and collecting ducts (HA10, C) remain. At the tip of the pyramid, the collecting ducts penetrate the urothelium covering the papilla (not shown) and deliver urine into a minor calyx (HA1).