Study of h-TSH immunoreactive adenohypophyseal cells following treatment with methymazole.

The TSH-producing adenohypohyseal cells of Wistar rats were studied after treatment with orally administered methymazole by the PAP immunocytochemical method. These cells were compared with those of normal animals. The effects of methymazole were different in the females to those observed in males. In both sexes, the numerical density (number of TSH cells per 1000 microns 2) increased after treatment. The cellular and cytoplasmic areas increased in the females while they decreased in the males. The nuclear area and the nuclear area/cytoplasmic area ratio increased in the males and decreased in the females following treatment with methymazole. This treatment caused the appearance of large, intensely stained cells, with an eccentric nucleus and cytoplasmic processes accompanied by weakly stained cells that were situated close to blood vessels.