Poliovirus 1. Poliovirus was purified and prepared for negative contrast electron microscopy. This image shows uniform 29 nm (nanometer) virions arranged in pseudocrystalline array. It is just that isometric particles often fit together in six-fold, two-dimensional array, as had occurred here on the background support film. Their array is like the arrangement that peas take when shaken in a pan. Magnification approximately x200,000.
Micrograph from J. Esposito, Centers for Disease Control and Prevention, Atlanta, Georgia, and F. A. Murphy, University of Texas Medical Branch, Galveston, Texas.