IMMUNOCYTOCHEMICAL EFFECTS OF THYROXINE STIMULATION ON THE ADENOHYPOPHYSIS OF DWARF (DW) MUTANT MICE

The effects of dietary thyroxine on the immunoreactivity of cells in t he pars distalis of the adenohypophysis in dwarf (dw/dw) mice were det ermined by ultrastructural immunocytochemistry. In nontreated dwarfs o nly adrenocorticotropic hormone (ACTH) cells and luteinizing hormone ( LH) cells showed positive reactions to their respective antibodies, wh ereas no cells showed immunoreactivity to antibodies to growth hormone (GH), thyroid-stimulating hormone (TSH), or prolactin (Prl). In dwarf s supplemented postnatally with dietary thyroxine for 9 wks, the treat ment failed to produce immunoreactive GK, TSH or Prl cells. However, L H cells became more prominent and fully developed, with denser concent rations of immunoreactive particles overlying the secretory granules t han occurred in nontreated dwarfs. In thyroxine-treated dwarfs, ACTH c ells were similar in ultrastructural features and immunoreactivity to those in nontreated dwarfs.