Abstract
Serial sections of vertebrate hypothalami were stained with the immunocytochemical peroxidase-antiperoxidase method. In addition to the single staining method, our double staining method was used, which enabled us to visualize two tissue antigens in single tissue sections. In both staining methods, differentially adsorbed antineurohypophysial hormone sera, anti-somatostatin serum and anti-bovine neurophysin sera were used. The results confirm the one hormone, one neuron hypothesis.