Lead phosphate deposition technique was used to investigate the changes and characteristic distribution of ATPase activity in the paranodules of tabacoo. We found that ATPase activity was closely associated with cell type and cell developmental state, thus it was different in various cells and rhizobia. No lead phosphate granules were located in the menstematic cells, although there were a small number of lead phosphate granules in the cytoplasm and organelles of the cells without rhizobia, they did not exist in the young and mature rhizobia. On the contrary, upon the senscence of the cells and rhizobia, a large number of lead phosphate granules appeared on the plasmalemmas and in the cell walls and the inside surfaces of the rhizobia. When the cells and rhizobia progressively senesced, lead phosphate granules increased in number, and they were widely distributed on the tonoplasts, plasmalemmas, cell walls, intercellular layers and in the intercellular spaces. At the same time, they also appeared on the surfaces and in the cytoplasm and nucleoids of the rhizobia. Due to cell disintegration, lead phosphategranules obviously decreased in number, they were only located on the plasmalemmas and membrane-vesicular structures which came from disintegrated organelles.