The effect of antidiuretic stimuli on the morphology of the lateral intercellular spaces in the medullary collecting duct of the rat.

An investigation has been carried out into the formation of dilated lateral intercellular spaces in the medullary collecting duct of the rat kidney following water deprivation or infusion of vasopressin. Dilation is conspicuous under these conditions, by comparison with normally hydrated controls, but its appearance is prevented by prior treatment of rats with antiserum raised against urinary (renal) hyaluronidase. Antiserum against testicular hyaluronidase is without effect. The presence or absence of dilatations in the lateral intercellular space correlates closely with previous findings on the ability or inability of rats to concentrate their urine under identical experimental conditions. It is concluded that urinary (renal) hyaluronidase plays an important role in the formation of such dilatations and that these facilitate the process of urinary concentration.