Yellow yolk granules by ESEM. Hardboiled hen's egg yolk was examined in hydrated state (no fixation, no dehydration, no gold coating) by environmental SEM (ESEM). In the egg yolk the granules were tightly packed to form a compact mass. Cutting with a blade revealed the granular microstructure. The environmental scanning electron microsope or ESEM is a scanning electron microscope that allows for the option of collecting electron micrographs of specimens that are "wet," uncoated, or both. Enhanced ESEM. Image width: 413 micrometers. Magnification: 242x if the image is printed 10 cm wide. Bar: 100 micrometers.