The ultrastructure of some gastrointestinal lesions in experimental animals and man.

This has been a brief and necessarily selective review, covering only a few of the numerous experimental and diagnostic uses of electron microscopy in the field of gastroenterology. The roles of experimentalist and diagnostician have emerged in a kind of counterpoint. We have identified the contrasting themes of the controllable laboratory experiment and the uncontrollable experiment of disease; of the three-dimensional image of the surface scanning technique and the two-dimensional world of the thin section. There is harmony, also, in our common concern for morphology and our shared interest in any structural change. Altered morphology, whether in tissue architecture or cellular organisation, may offer a key to the better understanding of altered function. In the future, both the experimental and the diagnostic electron microscopist will come to rely more on correlative procedures, such as the re-processing of specimens for a second look with a different technique. Functional dividends are promised to the morphologist by advances in detector technology and associated techniques such as analytical microscopy. It remains to be seen whether medical benefits will accrue, in terms of a more precise diagnosis or a more effective prognosis in individual cases of human gastrointestinal disease.