High-pressure frozen rat pancreas tissue samples were cryo-fractured
and cryo-sectioned with a diamond knife in the microtome of a
freeze-etching device. The bulk fracture faces and block faces were
investigated in the frozen-hydrated state by use of a cryo-stage in an
in-lens SEM. With this combination, relevant biological structures can
be investigated with a few nanometers resolution in a near lifelike
state, preventing the artifacts of conventional fixation techniques.
Compared to TEM replica techniques, the presented method is more
versatile since no replica cleaning is necessary. Additional structures
can be made visible by controlled sublimation of ice, leading to a
better understanding of the three-dimensional organization of
organelles, such as the endoplasmic reticulum.