Fine structure of mitochondrial helical filaments revealed by computer image analyses

In order to clarify the fine structure of the helical filaments appearing in the outer compartment of the mitochondria, Sprague-Dawley strain male rats were given 30% ethanol in drinking water for 90 days. The hepatic tissues of these animals were fixed with perfusion of glutaraldehyde via the portal vein followed by immersion in OsO4 and were then routinely processed for preparation of thin sections. Transmission electron micrographs of the sections were used for computer image analyses of the intramitochondrial helical filaments. With the application of the image analysis, it was revealed that the helical filaments show a right-hand rotating helix of 4.3 nm in thickness, 13.2 nm in diameter of the helix, and 15.7 nm in pitch. Also, with the multivariate statistical analysis and classification method of the IMAGIC image processing system, it was suggested in the classified images that the helical filament has substructures of rod-shaped particles of 4.3 nm in diameter. These particles are considered to be connected to each other and forming the helical structure of the filament.