Countercurrent exchange between the vasa recta and the loop of Henle.
D000818:Animals; D001692:Biological Transport; D007668:Kidney / Q000098:blood supply* / Q000502:physiology*; D007684:Kidney Tubules / Q000033:anatomy & histology*; D051381:Rats; D012082:Renal Veins / Q000033:anatomy & histology*; D014508:Urea
D014508:Urea