Electron microscopy of unstained, fresh air-dried spreads of the mouse brain and application to energy dispersive X-ray microanalysis.

Electron microscopy of unstained, fresh air-dried spreads of the mouse brain revealed well-preserved ultrastructures of neurons and synaptic boutons filled with synaptic vesicles. Energy dispersive X-ray microanalysis of the neuron nucleus disclosed peaks for phosphorus, sulfur, chlorine and potassium. Analysis of large regions (spots of ca. 1 micron in diameter) on the neuron nucleus revealed peaks for magnesium, whereas that of regions on the cytoplasm rarely disclosed the element, which was confirmed by removal of the background noise using a micro-Edit computer system. Analysis of regions on synaptic boutons except mitochondria also indicated peaks for magnesium.