Abstract
The relationship between the amount of rat mast cell protease I (RMCP I) in the granules and the stainability of granules was examined using the peritoneal mast cell of the Sprague-Dawley rat (6 weeks old). Epon sections of rat peritoneal mast cells were stained immunohistochemically for RMCP I, and observed with an electron microscope. Consecutive sequential light microscopic sections were stained with toluidine blue O. Photographs of electron microscopy and light microscopy of the same mast cells were compared each other. The dark violet granules with toluidine blue O contained the largest amount of RMCP I, the purple or intermediately stained granules less amount of RMCP I, and the pink granules slight amount of RMCP I. The mast cells, which were fixed with glutaraldehyde and osmium tetroxide and stained with alcian blue-safranin, followed by epon embedding, showed various colors of granules, if roughly divided, safranin positive, intermediately stained, and alcian blue positive granules. These sections were further stained with toluidine blue O and it was found that the safranin positive, the intermediately stained and the alcian blue positive granules with alcian blue-safranin double staining corresponded to the dark violet, purple and pink granules with the toluidine blue O staining, respectively. Thus it was concluded that light microscopic observations by toluidine blue O staining and/or alcian blue-safranin O double staining which is more generally accepted in regard to the distinction of mast cell granules than toluidine blue O staining enabled us to estimate the amount of RMCP I in the mast cell granules. This result will be useful to interpret the functional activity of mast cell populations in various physiological and pathological conditions.
