Demonstration by immunoperoxidase histochemistry of calcitonin in the anterior lobe of the rat pituitary.

We have demonstrated by a specific immunoperoxidase procedure the presence of calcitonin-containing cells in the rat pituitary gland. These cells are widely distributed throughout the anterior lobe and seem to constitute the entire population of cells of the intermediate lobe. No such cells were seen in the posterior lobe. The presence of calcitonin-containing cells in the pituitary provides novel implications about the physiological significance of this hormone.