which prompted conc-rn, have been removed at the University in Salt Lake Cty. The srplication ot -:-;. same criteria of judgement of radiation effect in thyroids excises: from this . --Jation has revealed only an oceasional thyroid tiss: which hints at ai. tion effect, contrary to the judgement of some reviewed the micr~:... pic preparations of these cases. The Study of Morphc:: ic Changes in Human Thyroids Previously Treated wi In the past year, unfortunately, there has been no patients previous] treated with 1512 for hyperthyroidism and studied extensively in or series that has had reason for thyroid surgery. Opportunities to obtain tissues for study occur in a random fashion and only when a mass develops causes concern. The Relationship of Bizarre Nuclear Forms to the Persistence of LATS in P Treated for Graves’Disease and Previously Studied Although we partially remove or partially destroy the excessively fu thyroid in Graves' disease to correct hyperthyroidism in man, the unknown Bri force that makes the thyroid overactive probably continues for a time. stimilus in its effect may be comparable in some respects to the stimilus phich is created by giving antithyroid drugs to normal rats. We know that antit! id drug treatment to rats previously treated with 1511 makes the bizarre nmlear much more evident. The reason why we find bizarre nuclear forms in some +F treated human thyroids and not in others may be because of the contimed s to hyperplasia in some of the patients. Although we must acmit we are fixms us convinced that the long acting thyroid stimulator (LATS) is the mechanism drives the thyroid in Graves’ disease, it is demonstrable in at least ta these patients before treatment. We have the LATS assay method firmly es in our laboratory. Although, as stated above, we had no opportunity to obfa radiated human thyroid tissue durins thepast year and to carry out our usp studies with special attention to the occurrence of bizarre forms in such pa when the opportunity does arise we expect to see whether the presence of Ls the serum has any relationship to the bizarre miclear forms fad in somei man thyroids which have not been too seriously damaged from 1311.