Further Observations on the Virus of Epizootic Diarrhea of Infant Mice. An Electron Microscopic Study

Abstract The particulate form of the virus of epizootic diarrhea of infant mice first appears as a single-membraned spherical structure, the central body, in cytoplasmic viroplasm. A nucleoid develops in the central body which moves into the cisterna of the endoplasmic reticulum (ER). In doing so it acquires a segmented “shell” which has an outer unit membrane. However, many particles without a shell and particles without nucleoids are present within the ER cisternae. Tubules bounded by a single membrane are present in the nucleus of infected cells and single- and double-membraned tubules of about the same diameter as the virus particles are present in the cytoplasm. Their role in the virus life cycle is not known.