Figure 1. Tomato Bushy Stunt Virus solution prepared by cryonegative staining. Bar, 250 nm. Virus, courtesy J. Witz; micrograph, M. Adrian.

Figure 2. Closed, circular, 1868 base pairs, supercoiled deoxyribonucleic acid (DNA) molecule (pUC 18 fragment). Left and right images form a stereo pair from which a three-dimensional model has been determined (middle). Micrograph, Eric Larquet; model, Catherine Zucker.

Figure 3. Three-dimensional structures obtained by electron cryomicroscopy. (a) The hepatitis B virus core protein shell contains 240 subunits arranged as 120 dimers. This reconstruction has 0.74 nm resolution, the virus diameter is 37.0 nm. Reproduced with kind permission from Böttcher et al. (1997). A similar structure was obtained by Conway et al. (1997). (b) Aquaporin 1 from red blood cells is constructed from six rod-like helices that surround a central water pore, indicated by the cone (Walz et al., 1997). This three-dimensional map has a resolution of 0.6 nm; the diameter of the protein in the horizontal membrane plane is 3.2 nm. The ‘floor’ in this image is an example of a two-dimensional image from electron cryomicroscopy after image treatment. Figure kindly provided by B. Heymann, University of Basle, Switzerland.

Figure 4. Thin vitreous section of partially decondensed stallion spermatozoa. Deoxyribonucleic acid (DNA)–protamine filaments are arranged in hexagonally packed bundles. The distance between filaments is 2.7 nm. Preparation and micrograph by Nathalie Sartori Blanc.