Whereas the peritubular capillaries surround the cortical parts of the tubules, the vasa recta go into the medulla and are closer to the loop of Henle,[1][2] and leave to ascend to the cortex.

[3][4] Terminations of the vasa recta form the straight venules, branches from the plexuses at the apices of the medullary pyramids.

They run outward in a straight course between the tubes of the medullary substance and join the interlobular veins to form venous arcades.

On a histological slide, the straight arterioles can be distinguished from the tubules of the loop of Henle by the presence of blood.

On the descending portion of the vasa recta, sodium, chloride and urea are reabsorbed into the blood, while water is secreted.