Further observations on the virus of epizootic diarrhea of infant mice: An electron microscopic study

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.