Abstract
Fresh sections from hamster adrenals were fixed in 10% formalin with 1% of CaCl. Fluorescence microscopy revealed fluorescent cell groups in the peripheral parts of the medulla; the center was non-fluorescent. Contralateral adrenals immersed in a saturated solution of potassium iodate and cut after fixation in 10% formalin showed brown cell groups in the peripheral medulla, and the distribution of the iodata-positive medullary cells was closely similar to that of the fluorescent cells in the formalin-fixed sections. Together with previous observations, the data are taken to indicate that the norepinephrine-secret-ing adrenomedullary cells can be shown by both the fluorescence method and the iodate method, which give a negative reaction with epinephrine.