Morphological examination of the juxtaglomerular apparatus following the fluorescence microscopic demonstration of sympathetic nerves

Several catecholamine demonstrating fluorescence techniques based on the formaldehyde-condensation principle have been examined for the possibility of application of juxtaglomerular granulum demonstrating methods. Freezing and thawing cause a distruption of juxtaglomerular granules. Short formalin fixation does not prevent this damage. Juxtaglomerular granules were successfully stained after freeze-drying. The adaptation of Endes's trichrome method on the basis of the classical catecholamine technique of Falck and Owman resulted in a reliable practical method. Procedures introduced into the trichrome methods to increase the colour and intensity contrast of the staining of juxtaglomerular granules and to stain the elastic membranes are described. Some aspects of the staining mechanism of juxtaglomerular specific granules are also discussed.