Autoradiographic Localization of Iodide125 in the Thyroid Epithelial Cell

Abstract

At short time intervals after injection of iodide¹²⁵, the concentration of inorganic iodide¹²⁵ in the thyroid epithelial cells of some follicles was much higher than in the lumen of the follicle or in blood vessels as demonstrated by autoradiographic methods. This finding in both binding and propylthiouracil-blocked thyroid glands suggests that the basal cell membrane is responsible for iodide concentration. The persistence of an autoradiographic image over the follicular cells for at least 5 minutes after iodide¹²⁵ injection suggests that the apical cell membrane exerts some control over the passage of radioiodide from the cell into the follicular lumen.