Abstract
The localization of peroxidase in pig thyroid gland was investigated by staining histochemically thyroid slices previously fixed with glutaraldehyde-formaldehyde or unfixed. The reaction product was localized mainly at the membranes of endoplasmic reticulum. Golgi apparatus and microvillous apical cell border did not seem to show a significant amount of the reaction product. Nuclear envelopes and nucleoplasm never displayed the dark material. These results are in good agreement with our biochemical results obtained previously by fractionating the thyroid homogenate. Significance of these findings relating to the site of peroxidase is discussed in connection with the iodination of thyroglobulin in the thyroid follicular cells.
