[Muscle cell structure in polymyositis].

Electron microscopic investigations of muscles from patients with chronic polymyositis demonstrated presence of cytoplasmatic, tubular structures and extracellular virus-like particles. Their size, morphology and location suggest multiplication of viruses from the group of parainfluenza viruses within the muscle cell in "infected" cultures of human fetal muscles. Beside viruses belonging to the parainfluenza group presence of viruses from the herpes group was demonstrated. The latter belong to latent viruses.