Three-Dimensional Fine Structure of Cells and Tissues
From BTRR
Overview
High-voltage electron microscopy (HVEM) offers scientists the possibility of viewing structural details in specimens whose thickness defies imaging by other forms of EM. This permits better three-dimensional (3-D) reconstruction of cellular architecture at resolutions ~40X than can be achieved by light microscopy. Relevant samples include thick sections (200–500 nm) of cells and tissues or isolated organelles, such as chromosomes, chloroplasts, mitotic spindles, and axonemes.
Stereo images can supply some 3-D information, but more detailed data are available from tomograms calculated from multiple tilted views, e.g., 150 images taken over 140º of tilt about each of two orthogonal axes. The resulting reconstructions show resolution of ~6 nm. This facility is also developing technology for the preparation of reliable cellular specimens. High-quality preservation can be achieved through rapid freezing with or without subsequent freeze-substitution fixation. The resource also is working on specific labeling of macromolecular components of cells, both by conventional immunolabeling and by novel means. Methods for tomographic imaging of frozen hydrated samples are also under development.
