A coat of glycoconjugates on the inner surface of the lysosomal membrane in the rat kidney.

After perfusion fixation of the rat kidney with glutaraldehyde, and postfixation of the renal cortex with osmium-low ferrocyanide (40 mM OsO4 +6 mM K4Fe(CN)6 in 0.135 M phosphate buffer, pH 8.0), secondary lysosomes of proximal tubule cells carry a coat of electron dense material on the inner surface of the lysosomal membrane. This coat separates matrix and membrane of lysosomes, and corresponds in location and width to the electron translucent halo of conventionally processed lysosomes in TEM. The material which forms the coat, is stained by phosphotungstic acid at pH 0.3, and by periodic acid - thiocarbohydrazide - silver proteinate more intensively than the cell surface coat of the same cell; it contains a high concentration of hydroxyl, vicinal-glycol and alpha-aminoalcohol groups.