Electron-dense Crystallites in Nuclei of Human Amnion Cells infected with Measles Virus

MEASLES virus antigen has been specifically identified in the nuclei of infected cells by means of the fluorescent antibody technique; and the development and spread of virus antigen in amnion and other human cells have been correlated with observations made in a concurrent study of fine structure 1 . During a continuation of the latter investigation we have found that crystallites made up of ordered arrays of electron-dense particles occur within nuclei of infected human amnion cells, and have also observed extracellular particles that can be interpreted as mature virus.