Transmission electron micrograph of Adenoviruses. The viruses are about 80nm in diameter, and do not have the lipoprotein envelope associated with many other virus genera. The genome of the adenovirus is double stranded and linear DNA. Adenoviruses were first isolated from human adenoidal glands, and are the causative agents of many respiratory diseases. Magnification: x340,000 at 6.5"x8.5" size.