[Immunoelectron microscopic study of growth hormone cells in hyper- and hypothyroid rats]

Male Sprague Dawley rats were rendered hyperthyroid and hypothyroid by the intraperitoneal injections of 1-thyroxine or methimazole and sacrificed 21 days after the start of the treatment. The pituitaries were studied by immunoelectron microscopy by the immunogold labeling technique. In both hyperthyroidism and hypothyroidism, the numbers of growth hormone (GH) cells, GH-secreting granules and immunogolds in the secretory granules all were significantly decreased as compared with those in controls. The results indicate that low or high levels of thyroid hormones may cause decrease of GH production of the pituitary.