Identification of renal neuroeffector junctions by electron microscopy of reembedded light microscopic autoradiograms of semithin sections

Abstract

A method is described for the identification of renal neuroeffector junctions using electron microscopy of reembedded autoradiograms of semithin sections. Tritiated norepinephrine is used to identify renal monoaminergic nerves. Although this study focused on the relatively infrequent neuroeffector junctions with the tubules, junctions with arteriolar cells were also investigated. Autoradiograms containing accumulations of grains associated with tubules or arterioles were first photographed with the light microscope, then reembedded, ultrathin sectioned, and examined with the electron microscope. Electron microscopy consistently disclosed nerves at those sites where accumulations of grains were observed by light microscopy. Neuroeffector junctions and nerve proximity to renal tubules (proximal and ATLH) could be predicted with considerable accuracy at the light microscope level by the degree to which the autoradiographic grains overlapped the tubular- walls. This criterion was also applicable to neuroeffector junctions with the arterioles. This method may be useful for the electron microscopic study of structures that can be autoradiographically labeled but which are infrequent or too small for light microscopic analysis. Other potential uses of this procedure are suggested.