The experimental production of thyroid tumors in the rat exposed to prolonged treatment thiouracil

Abstract

T HE conditions under which a normal tissue undergoes transformation to a pathological state are at present not well understood.A vast amount of literature exists on the changes induced in various tissues under the stimulation of different carcinogens.However, until recently, little information was available on the histological changes produced in endocrine tissues by stimulation with foreign agents.Until the advent of thiouracil and other goitrogenic drugs, little evidence existed to show what experimental and pathological changes could be produced in the thyroid gland by drugs or diets.Slye, Holmes, and Wells in 1926 described a small number of spontaneous thyroid tumors in a large series of rats and mice.Others have occasionally reported the occurrence of spontaneous thyroid carcinoma in similar species of animals.The first reports on an experimental approach to this problem were those of WegelinZ0 and Hellwig.Wegelin reported the presence of thyroid adenomas in rats maintained on a diet that produced thyroid hyperplasia.He, therefore, concluded that thyroid neoplasia was preceded by thyroid hyperplasia.Hellwig maintained rats on an iodine-deficient, calcium-rich diet for a fairly long period of time, and reported the presence of thyroid tumors in his animals.I n 1945, Griesbach, Kennedy, and Purves reported the induction of thyroid tumors