The transmission electron microscope was the result of Ernest Ruska’s doctoral project under the guidance of Max Knoll. This event marked a new era in microscopic observation since the year 1930. The resolution of this instrument allows for atomic-scale observation, surpassing all other microscope variants, including super-resolution microscopes. This microscope features an electron gun that operates at high energy (more than 100 kilo-electron volts), a column with electromagnetic lenses, apertures to control the electron beam, and a sample chamber located at its center. Extending from the column is the projection chamber, where a phosphor screen is located. When it encounters the electrons transmitted through the sample, the screen produces a projection of the image with a characteristic green tone. The sample requires precise and meticulous preparation, which can take several hours or days. Fixation and embedding treatments depend on the purpose of the observation. Sections of approximately 60–90 nm in thickness are placed on grids, with characteristics depending on the size of the sample and the observation objective.