Histochemical Adenosine Triphosphatase Activity in Dark and Light Cells of Collecting Tubules in the Mammalian Kidney

Abstract

IN the kidneys of various species, the collecting tubules are composed of two types of cells. These were apparently first seen by Heidenhain¹, and described in subsequent years as light and dark (intercalated) cells². The name given to these cells alludes to the fact that the cytoplasm of the dark cells stains with various commonly used dyes more intensely than that of the light cells. The dark (or intercalated) cells reveal also strong metachromasia³. Electron micrographs show that the dense cytoplasm of the dark cells contains more RNA granules than the cytoplasm of the light cells. Mitochondria are more numerous in the dark cells and are localized not only in the basal but also in the apical portion of the cytoplasm⁴. In contrast, electron-dense granules are more numerous in the light cells than in the dark cells. These granules are composed of phospholipids and proteins and contain one or several crystals with a hexagonal or square lattice⁵.