Deoxyribonucleic Acid Content Associated with Nuclear Changes in131I-Irradiated Human Thyroids

Abstract

Samples of tissue from human thyroids previously treated with ¹³¹I for hyperthyroidism and subsequently studied extensively for early and late radiation effects have ultimately become available for morphologic study. A microspectrophotometric method has been used to measure the amount of DNA in individual nuclei. Doses of ¹³¹I just sufficient to bring hyperthyroidism slowly under control but not to produce significant architectural derangement result in increased nuclear DNA and variations in amounts of DNA and nuclear volume. Such changes correspond to the occasional bizarre nuclear forms previously recognized in such thyroids. The amounts of DNA in individual nuclei are sometimes found to surpass 2 times the diploid value, the level at which division of the cell should occur. Evidence suggests that this is thwarted cell division and probably explains the ultimate failure of thyroid function year3 after a euthyroid state had been achieved by ¹³¹I therapy. Thyroid tissue from non-irradiated patients and from others who had received Xradiation to the cervical area are abo included in the study for comparison.