Diagnostic ultrastructural pathology--sub-speciality or special stain?

The high resolving power of the electron microscopy gives ultrastructural pathology many of the features of a 'sensitive, multipurpose stain'. But the high resolution gives rise to problems of evaluation since most pathological features of disease are specific in a quantitative rather than in a qualitative way. Thus, pathological changes may be of diagnostic importance when they are severe enough to be seen by light microscopy, but less so when only revealed by electron microscopy. Problems of evaluation and interpretation should not lead to paralysing nihilism but should make us realize that electron microscopy does not represent the ignorant pathologist's key to a diagnostic heaven, no more than do special stains, histochemistry and immunocytochemistry. At present it may be necessary to organize ultrastructural pathology as a kind of sub-speciality of pathology. In the long run, we feel that sub-specialities should be related to the object studied rather than to the instrument used. Thus, the neuropathologist should do ultrastructural neuropathology, the cytologist ultrastructural cytopathology, etc. in the same way as most kidney pathologists already do their own ultrastructural work.