Low Noise Electron Microscopy by Merging Multiple Images Digitized from Conventional Films with Reference to the Mouse Kidney

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 x10,000, x13,000, and x63,000, 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.