Specific staining of the thyroid follicular cell apical membrane by nitroblue tetrazolium

Nitroblue tetrazolium (NBT) has been widely used to demonstrate redox systems, particularly in phagocytizing polymorphonuclear leukocytes. Based on the striking similarities between redox metabolism in leukocytes and in the thyroid, we studied NBT reduction by microscopic techniques and NBT effects in thyroid metabolism in dog-thyroid slices in vitro. We observed specific localization of NBT reduction product along the apical membrane of the follicular cell. Hence, NBT is a potentially useful market of thyroid-cell polarity.