Effects of the anti-thyroidal compound potassium-perchlorate on the thyroid system of the zebrafish

► We investigated the effects of perchlorate on the thyroid system of the zebrafish. ► In the thyroid, the colloid reacted most sensitive to the exposure to perchlorate. ► The pituitary displayed statistically significant increases of TSH-producing cells. ► A histologically observable increase of adenohypophyseal tissue was observed. ► Glycogen depletion could be observed in the liver.