FINE STRUCTURAL LOCALIZATION OF PERIODIC ACID-THIO-CARBOHYDRAZIDE-SILVER PROTEINATE REACTIVE SUBSTANCES IN RAT THYROID FOLLICULAR CELLS

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Rat thyroid gland tissues, fixed in various fixatives, were stained by means of the periodic acid thiocarbohydrazide silver proteinate (PA-TCH-SP) method of Thiéry and observed at the ultrastructural level. In electron microscopic observations, the cell organelles showing positive reactions were the Golgi apparatus, subapical granules, reabsorbed colloid droplets, lysosomes of follicular epithelial cells and colloid of the follicular lumen. The effect of fixatives was compared with respect to the differences in stainability. In each tissue fixed either with glutaraldehyde and osmium tetroxide or osmium tetroxide, only a trace of the silver reaction product was discernible. One hr treatment of TCH was not sufficient for tissues fixed singly with either paraformaldehyde or glutaraldehyde, and the stainability was strongly intensified by prolongation of TCH immersion, especially in tissues fixed only with paraformaldehyde. To intensify the PA-TCH-SP reaction, “protonation” with acetic acid and “etching” using potassium hydroxide were performed on the sections fixed singly in osmium tetroxide or glutaraldehyde, respectively. Favorable results were obtained from each treatment. Though the PA-TCH-SP method is analogous to the PAS reaction in principle, it seems that the reaction is influenced by the kind of fixative and the amount of reactive sugar.