A combined fluorescence histochemical and electron microscopic method for studying special monoamine‐containing cells (SIF cells)

Abstract

Abstract This paper describes a method for locating “small intensely fluorescent” (SIF) cells on the basis of their monoamine fluorescence preparatory to study with the electron microscope. After fixation by perfusion with a formal‐dehyde‐glutaraldehyde mixture, the cells develop a bright yellow fluorescence easily seen when thick, unembedded slices of ganglionic tissue are examined with fluorescence optics. Once located, the same cells can then be studied electronmicroscopically following a second fixation with osmium tetroxide and Epon embedding. The resultant images are of good quality and highly reproducible. As an alternative to extensive sampling of plastic‐embedded ganglia, the method has the advantage of being less time‐consuming and more informative. Cells stored in fixative for months or embedded in paraffin retain their specific fluorescence. Since the particular fixative used is compatible with a variety of neurohistological and histochemical techniques, the method provides unprecedented opportunities for correlative studies employing fluorescence, light, and electron microscopy. The method can also be applied to glomus cells of the carotid and aortic bodies and to adrenal medullary cells.