Microwave-enhanced silver staining of degenerating neuronal processes.

A simple and rapid method for light and electron microscopic visualization of degenerating neuronal processes and axon terminals is described. Hundred-micrometer vibratome sections of perfusion-fixed rat brain were incubated briefly in a 5% silver nitrate solution in a conventional microwave oven. After a rinse in 1% acetic acid, the sections were silver enhanced. Differentiation and counterstaining was done respectively in ethanol 100% and cresyl violet. In the light microscope, degenerating neuronal processes appeared as black dots against a clear background. Areas of calcification were also positively stained. The presence of silver deposits in degenerating presynaptic terminals and dendrites was confirmed ultrastructurally.