The Paraganglia

Our knowledge of chromaffin tissue has increased enormously since the last comprehensive treatise in this series was published in 1943, chiefly as a result of the development of new histological methods and technical improve- ments. Less than 40 years have passed since the review by MAX WATZKA, and essentially only 25 years were required to accumulate an abundance of revolu- tionizing findings: it was not until 1957 that the carotid body was first studied successfully with the electron microscope. In 1962 the technique of formalde- hyde-induced fluorescence was introduced, yielding a view of adrenergic struc- tures that was completely new and far better than that obtained with the chro- maffin reaction. Immunohistochemistry made it possible to localize enzymes responsible for catecholamine synthesis and to detect peptide hormones. Autora- diographic techniques were used at the level of the electron microscope, the method of chemical sympathectomy was introduced and still other technical improvements could be mentioned. I myself have been interested in chromaffin cells and sympathetic neurons since 1965, when I entered the Department of Histology, University of Vienna, as a medical student. Therefore I have not followed the developments mentioned above retrospectively, but have actually experienced them. Anyone who experi- ences such a development comes to believe that he is well acquainted with the various results and interpretations and is thus capable of objectivity.