FINE STRUCTURE OF THE CELLS RESPONSIBLE FOR SECRETION OF ADRENOCORTICOTROPHIN IN THE ADRENALECTOMIZED RAT

Adrenalectomy cells, previously demonstrated by autoradiography in the light microscope as the site of ACTH production in the adrenalectomized rat, were identified in the electron microscope by their peculiar morphology. The adrenalectomy cells were found to have certain characteristic fine structural features which aid in identifying and differentiating them from the other cell types. Their secretory granules, with a maximal diameter of about 200 mμ, are larger than thyrotroph granules, smaller than acidophil granules, and correspond in size roughly to the gonadotroph granules. Gonadotrophs are readily differentiated from adrenalectomy cells, however, by their typically rounded shape. (Endocrinology 76: 70, 1965)