AUTORADIOGRAPHY OF DIFFUSIBLE IONS WITH APPLICATION TO THYROIDAL RADIOIODIDE

Abstract

A method for the autoradiographic localization of water-soluble diffusible ions has been developed and applied to the localization of iodide125 in the mouse thyroid gland. Frozen-dried thyroids of hypophysectomized mice containing radioiodine125 as inorganic iodide125 were embedded in paraffin. Sections were spread on mercury and mounted on autoradiographic film. After exposure the mounted section was permanently fastened directly over its latent image and tissue constituents were fixed by dipping in 80% aqueous methanol. The preparation was air dried and then deparaffinized with petroleum either. After development and fixation, slides were stained with Nuclear Fast Red. In certain cases radioiodide could be localized primarily in the follicular epithelium. Control studies demonstrated that the autoradiographic image was not an artifact resulting from chemical induction or suppression of selected areas of latent image. A comparison of autoradiographs prepared from frozen sections and those prepared by freeze-drying showed similar localization of the radioisotope and indicated that there was no displacement of the radioiodide during paraffin embedding.