Figure 2. Treatment schedules for the study groups.

Forty six mice were given propylthiouracil (PTU), thyroxine, both in drinking water, or tap water (control) for 21 days. Six mice from each group were then removed in order to measure FT₄ levels (Thyroid status), after which they were sacrificed. Of the remaining 28 mice—9 given PTU, 11 given thyroxine and 8 given tap water (Experimental groups)—were inoculated with tumor cells (day 0) and monitored daily, and first sign of intraocular tumor growth was recorded. The time from inoculation to spontaneous death was defined as the survival time. The internal control consisted of 11 additional mice, 3 given PTU, 4 given thyroxine and 4 given tap water; they were not inoculated with tumor cells. These mice were followed-up and sacrificed 2 months after the last experimental mouse had died (blood samples had been obtained for FT₄ level determination beforehand).