Atomic force microscopy observation of native neurons and modifications induced by glutamate

We used an atomic force microscope, in the repulsive regime of contact mode, to take images of uncoated neurons fixed in glutaraldehyde on a gold covered stainless steel substrate. We observed granule cells and their axons with a resolution better than 20 nm. The good stability of the sample and the mechanical reproducibility of the microscope allowed the imaging of a neuron culture area of several square microns. Modifications induced by glutamate on the neuronal culture resulted in observing a drastic reduction in cell granule height (from 1.5-2.0 mu m for the unperturbed ones down to 0.7-1.0 mu m) and in an increased corrugation of the surface membrane. The atomic force microscope images were very reproducible over repeated scanning acquisition, demonstrating a very good mechanical and thermal stability of the instrument-sample system. (C) 1996 American Vacuum Society.