Answer:
Vasa recta.
Step-by-step explanation:
Vasa recta are a group of capillaries, branching from the peritubular capillaries and moves parallel with the loop of Henle. Vasa recta is responsible for the supply of blood to renal medulla in order to purify the blood from the waste materials such as salts, excess water and nitrogenous waste etc. Due to its movement with the loop of Henle, it slows down the blood flow which helps in the re-absorption of water.