Electron microscopy

Specimen:

Both tissue and virus samples may be examined by electron microscopy.

If electron microscopy studies are contemplated laboratory staff should be contacted in advance.

  1. Main tissue types for electron microscopy investigation include:

    needle biopsy of the kidney for typing Glomerulonephritis;

    tumour sample for typing poorly differentiated tumours;

    liver or other tissue for inherited metabolic disorders;

    sural nerve for peripheral Neuropathy;

    muscle biopsy for Myopathy; and

    turbinate biopsy for primary ciliary dyskinesia.

  2. Virus samples include: blister fluid, swabs, and faecal suspension.

Method:
  1. Tissue must be fixed as quickly as possible: this may necessitate collection from theatre. 

    Tissue is fixed in a buffered glutaraldehyde/formaldehyde fixative, cut into pieces less than 1mm in size, dehydrated, embedded in plastic, sectioned and examined. 

    Paraffin embedded tissue for light microscopy can be used retrospectively for electron microscopy. When it is reprocessed for electron microscopy, this tissue can provide useful information.

  2. Viral sample is placed on a grid, negatively stained with a heavy metal salt and examined.

Application:

Electron microscopy is useful for rapid viral identification and is important for typing Glomerulonephritis. 

In tumour diagnosis where results from morphology and antibody labelling are equivocal electron microscopy can provide useful additional diagnostic information. 

For the other conditions such as metabolic inherited disorders, peripheral neuropathies, myopathies and primary ciliary dyskinesia, electron microscopy can provide a definitive diagnosis.

Interpretation:

Requires experience in electron microscopy.

Reference:

EM Techniques:

Stirling J. Diagnostic electron microscopy 1st ed 2013 Wiley