Path. Res. Pract. 167, 1-2 (1980)

Diagnostic Electron Microscopy

Editorial

This special issue of Pathology Research and Practice presents authoritativearticles on the present state of diagnostic electron microscopy applied to virol­ogy, oncology, renal, and metabolic disorders.

The electron microscope is now an established routine tool in diagnosticpathology. It does not replace the light microscope but rather represents anextended arm breaking through the resolution barrier of light optics andbringing the interpretation of disease down to the subcellular level.

With the use of rapid preparation procedures like negative staining andrapid embedding methods, it is even possible to obtain a diagnostic electronmicroscopy answer minutes to hours after the receipt of the material to beexamined.

Sophisticated techniques such as imrnuno-electron microscopy, ultracy­to chemistry, cryoultramicrotomy, X-ray diffraction, electron probe X-rayanalysis and more or less automatized stereological methods are also availableand may gain increased diagnostic importance in the years to come. Theirapplication to human pathology has only just started, and even scanningelectron microscopy of human diseased tissues is in its infancy.

The refinement of the procedures mentioned has been parallelled by anincreased awareness among pathologists that even material of inferior qualitymay have retained enough ultrastructural clues to permit a diagnosis notpossible by light microscopy.

The use of large surgical specimens fixed in acid formaldehyde and maybeembedded in paraffin may not reveal new information of importance topathology in general, but may be very important for the individual patients byenabling the pathologist to make a correct unequivocal diagnosis as basis fortreatment and assessment of prognosis. Even autopsy tissues fixed several daysafter death may exhibit ultrastructural features of diagnostic importance.

The development of the electron microscope has also followed differentdirections, one aiming at advanced cell biologists or pathologists, the other atthe routine pathologist. While the first category demands the ultimate inresolution and versatility, the other may be more concerned with ease andspeed of operation as well as the best possible correlation to light microscopy.Until recently, the chief concern of most major manufacturers of electronmicroscopes was to meet the needs of the advanced electron microscopists. A

1 Path. Res. Pract. Vol. 167

2 . J. V. Johannessen

new breed of instruments have now been brought on the market however,incorporating light and electron optics in one and the same instrument. Thisenables the pathologist to examine a large, 5 mm diameter section by bothlight and electron microscopy. Such an instrument will no doubt make elec­tron microscopy more easily available to light microscopists who may at anygiven moment compare the ultrastructural findings with the light microscopi­cal appearance of the same structures. They also allow the pathologists tocompare light microscopical staining reactions with the ultrastructural fea­tures of the stained material.

When faced with a diagnostic problem in light microscopy, the pathologisthas ready access to text books and journals dealing with surgical pathology.The ultrastructural experiences gained during the last decades have howeverbeen scattered throughout a large number of books and both medical andnon-medical journals. Two recent book series, ELECTRON MICROSCOPYIN HUMAN MEDICINE (McGraw-Hill International Book Company) andDIAGNOSTIC ELECTRON MICROSCOPY (John Wiley) have been pub­lished to remedy this situation and a new journal ULTRASTRUCTURALPATHOLOGY (McGraw-Hill/Hemisphere) is in the process of being launchedas a forum for those working in diagnostic electron microscopy.

Major societies of pathology, like European Society of Pathology and Inter­national Academy of Pathology furthermore arrange courses and workshopson ultrastructural pathology for large and enthusiastic audiences.

The field of ultrastructural human pathology is more and more attractingthe interest of clinicians and cell biologists. The departments of pathology, aswell as individual pathologists with a solid basis in diagnostic light micros­copy still have the possibility of running the development instead of beingoverrun by it.

Jan Vincents Johannessen