QUANTITATIVE AND QUALITATIVE CHANGES IN THE "DARK" CELLS OF THE RENAL COLLECTING TUBULES IN RATS DEPRIVED OF WATER.

Abstract

There is evidence that the renal collecting tubule is involved in the final concentration of urine, but the fact that its wall is built up of two different kinds of cells has not hitherto been taken into account. The possible rôle of one of these, the “dark” cell, has been investigated by quantitative and qualitative methods. Collecting tubules were isolated by digestion in collagenase from the kidneys of normal rats and of rats deprived of water for 48 hr.; the dark cells were identified by staining with the Nitro BT method for succinic dehydrogenase. The number of dark cells was counted; the tubules were classified on a percentage basis into three groups, containing less than 30, 30‐50, and more than 50 dark cells respectively; cytological and cytochemical observations were also made. It was found that both quantitative and qualitative changes occurred in the dark cells of the dehydrated rats. It seems that these cells secrete into the tubule lumen. It is suggested that collecting tubules may differ from each other functionally. The results are discussed in relation to Ginetzynski's hypothesis that ADH causes hyaluronidase to be secreted into the collecting tubule.