Original transmission electron micrographs illustrating a variety of biological tissues are excellent tools that can be used in the education and examination of first year medical students. Many of these valued micrographs (and the negatives that produced them) date back to the 1960s, to the time when this researcher started a career in microscopy that continues to this day, To avoid returning to the darkroom and laborious photographic techniques, original negatives were scanned to produce micrographs for use in written or laboratory examinations or as images transported into Power Point lecture presentations. Original micrographs also were scanned and provided additional educational materials.

This article presents ideas on some topics related to electron diffraction in the TEM. These are in regard to topics that I have come to think of as standard parts of what it means to do microscopy. However, they represent insights that not all users share (or even agree with, maybe).

Kikuchi lines are of great use in orienting a sample. Unfortunately, in modern microscopes, Kikuchi lines are not seen in selected-area diffraction (SAD). This is because immersion lenses send parallel electrons, from different parts of the sample (like the Kikuchi lines from a flat specimen), to different places in the diffraction pattern.