THE LOCALIZATION OF ARYL SULFATASE ACTIVITY IN THYROID FOLLICLE CELLS
The localization of aryl sulfatase activity in thyroid follicle cells was studied with cytochemical techniques both on the light and the electron microscopic level. Twenty male rats received thyroxine to suppress the thyroid activity. To 10 of these animals, thyrotropic hormone (TSH) was given 15-140 min before sacrifice. In both experimental groups, there was dense precipitation indicating aryl sulfatase activity in the cytosomes. In the TSH-stimulated group colloid droplets were observed. These did not show aryl sulfatase activity, not even after prolonged incubation. The number of enzyme-containing bodies in the cytoplasm seemed to decrease after TSH-stimulation, probably because of fusion of colloid droplets with preexisting cytosomes. The lack of enzyme activity in colloid droplets is discussed and some possible explanations are offered.