False-colour transmission electron micrograph (TEM) of rotavirus particles (virions). Individual virions consist of an icosahedral protein capsid containing a core of double-stranded RNA which is fragmented into ten different segments. They have no lipoprotein envelope and are 65-75 nanometres in diameter. Rotaviruses are the major cause of viral diarrhoea in newborn animals of many species, including human infants, lambs and calves. Magnification: x75,000 at 6x4.5cm size.