THE ACTION OF VARIOUS GOITROGENS IN INHIBITING LOCALIZATION OF RADIOIODINE IN THE THYROID AND THYMUS GLANDS OF LARVAL TREE TOADS

Abstract

1. Larvae of Hyla versicolor were immersed for 15 days in spring water containing phenylthiourea, KClO4, KSCN, KClO3, or KIO3 followed by a 24-hour immersion in 20 µc./ml. of I131, a thyroid-destroying dose. 2. When treatment with any one of these drugs was continued during the period of I131 administration, radiation damage to the thyroid was prevented. 3. The inhibitory effect of KClO4 on the thyroid persisted even when treatment was discontinued two days before immersion in the I131 solution. 4. The effects of phenylthiourea and KSCN were dissipated more quickly since the thyroid showed extensive damage when treatment was stopped immediately before I131 administration and complete destruction when it was stopped two days before. 5. In control animals, the thyroid-destroying dose of I131 extensively damaged the thymus gland as well. 6. Of the drugs tested, only KClO4 sufficiently inhibited the I131 uptake by the thymus to prevent damage, and only when it was present during the period of exposure to I131.