Countercurrent System in the Renal Cortex of Rats

Abstract

Tubules on the surface of the renal cortex are intertwined with the capillaries. Micropuncture experiments on rats show that generally the flow of tubular fluid is against the flow of blood in the peritubular capillaries. A countercurrent flow system, therefore, exists not only in the renal papilla but also in the superficial cortex.