- U « microspectrophotometry on animal thyroids in this laboratcry, thel rigid methodology for procuring and processing the tissue was set into @peraticn each time human thyroid material was to become available. Thus, fhe quentitative measurement of DNA in individual nuclei was undertak@n in hemen ' tissue as we had done in the past in animals. Over a period of ajlaost 10 years, thyroid tissues from 12 131f treated patients were obtaine¢ study. All hed had Graves' disease. for this In addition, % tissues from/thyroids previously subjected to x-ray radiation and 2 controls were obtaiged. Ten of the 12“13iy patients were subjected to surgery because of masses which had developed in the thyroid; one patient wos operated on for pergistence of hyperthyroidien and was receiving an antithyroid drug at the timejthe tissue was cbtained; in two instances tissue was obtained at prompt post imortem examination. All tissues had been processed and stored in paraffin blocks so that simultaneous staining could be accomplished on all tissue lat the same time. Recently the final steps in the preparation and st these radiated During the past 1% ds and tissues from control thyroids were years the quantitative measurement of DNA in cor nuclei was done on these human tissuea. ng of lec individual Quantitative measurement of DNA in individual nuclei using Feuliger staining and microspectrophotometry showed considereble variation lin DNA than 2 tines the diploid value. This is as wes observed in the thyroids of animals which had previously been given 131r and is as a build up in DNA, but thwarted cell division. sti tt a" content and nuclear volume in some, but not all of tte radiated tiles Measurements indicated that the amount of DNA in some cells was gre isjtery On review of alternate sections stained with the customary hemats and eosin method, it was found that somewhat fewer of these radiat tissues displayed bizarre nuclear forms than was observed in our pf radiated human thyroids described many yerrs ago. However, four of 12 131r treated patients shoved an abundance of the bizarre miclear fpres in extranodular tissue. One of the most obvious was a patient who hai not been cured of hyperthyroidiam end had been given propylthiouracil before the cperation. This drug may have behaved in a fashion compareble to our animal experiments where an abundance of bizarre nuclear forms devplc when a similar stimulus was applied. In this case the natural st: alus of the disease to produce hyperplasia had obviously persisted at the Rime tissue was obtained. the In the other cases following 131I treatwent, it‘is difficult to know whether a given patient is in a euthyroid state because the driving force that caused Graves’ disease has abated .¢ whethef the . force is still there, but the thyroid is so damaged that hyperthyrpidiam is not possible. Some of the adenomas which developed in these radiated human gl were also similarly studied for MIA content of individual nuclei. [Contumors. In the figal analysis, it is not entirely clear which arose following 1311 and which were present, but not detected, at 131I was given. It would be particularly interesting to know whick arose from radiated cells that bore a potential for bizarre nucle because the tumor was @lready present. Certainly the former must tumors true in some cases, One follicular adenocarcinoma was encountered in alpatient tho had heen treated with 131], but unfortunately, the special pregarations on this neoplasm were not adequate for our studies. The bizarre