Observations on the localization of arylsulphatase activity in renal cortical tubules

Summary The fine structural localization of arylsulphatase in rat kidney cortex was investigated using p-nitrocatechol sulphate as substrate and lead as capturing ion. The studies included observations of the effects of different modes of fixative application in order to define optimal conditions for the histochemical procedure. Reaction product (lead sulphate) was constantly precipitated in the cytosomes in cells of proximal and distal convoluted tubules and collecting ducts. Previous studies have demonstrated that these same organelles contain acid phosphatase and appear to correspond to lysosomes in biochemically isolated fractions from renal cortex. The observations are compatible with the notion that most of the cytosomes in renal cortical tubules and collecting ducts contain both acid phosphatase and arylsulphatase. The constant absence of precipitate in microbodies of proximal tubule cells supported the assumption that these organelles are functionally different from cytosomes, and may correspond to peroxisomes.