In a conventional transmission electron microscope system, the
resolution is regarded as an absolute limitation, that is, 0.2 nm in
theory and 0.6 nm in sections of biological materials. However, in an
oversampled system, this limitation can be broken. In the present study,
60-nm-thick Epon sections from a mouse kidney were used. From these
sections tight junctions located in the distal tubule were selected as
test objects. Sets of up to 15 electron microscope images of the same
target were recorded on negatives at ×10,000, ×13,000, and
×63,000, respectively. The recorded films were digitized using a
light microscope equipped with a digital camera. In each set the images
were expanded, aligned, and merged into a more highly resolved output
image. Each output image revealed details in the tight junction, which
were not visible at the original magnifications. Two different sizes of
colloidal gold particles (10 nm and 1 nm) conjugated with an immunoglobin
G (IgG) served as references. With this improvement of resolution, it
becomes possible to inspect some barely visible biologic (virus) particles
and structures, such as glycogen and free ribosomes in their native
environment.