The thyroid glands of rats were made non-functional by a single dose of iodine-131 on the 1st day after birth or by surgical removal on the 28th day. The incorporation of sulfate-sulfur into the sulfomucopolysaccharides of skeletons and pelts was found to be significantly depressed by thyroidectomy. Daily supplements of 5 or 10 γ of L-thyroxine, started on the 28th day, increased the uptake of sulfur-35, although it did not reach normal in the 2 weeks of treatment.
Autoradiograms of sections of tibiae and pelts confirmed the analytical data. The findings suggest that the synthesis of sulfomucopolysaccharides is depressed in thyroidectomized rats.