Electron microscopy of urinary calculi--some facts and artefacts.

Material in urinary calculi is prone to irradiation damage during electron microscopy and this suggests the need for care in the interpretation of data. It is shown, however, that minimum-dose transmission microscopy is feasible for single-crystal electron diffraction work, and that although internal damage in severe, morphological artefacts are unlikely in the SEM unless the incident electron flux is greater than 10(-13) A nm-2. During EDX microanalysis, the detection of light elements is impaired by irradiation effects unless a minimum-dose procedure is used. For the preparation of SEM samples, artefacts can be created by cleaving air-dried material - and it is therefore important to consider more lengthy preparation methods such as cryogenics.