[Late stages in the replicative cycle of human cytomegaloviruses in diploid cells. Ultrastructural study]

An ultrastructural study of late stages of the replicative cycle of human cytomegalovirus (CMV) in human embryo fibroblasts cell cultures has been performed. Nucleocapsids are observed only inside the intranuclear inclusion. They mature apparently by taking the envelope from the structural components of microvescicular systems reaching from the nuclear membrane the periphery of the nuclear inclusion. However, some capsids reach "naked" the cytoplasm and then take the envelope from cytoplasmic membranes. In the cytoplasm homogeneous "dense material" and "dense microbodies" are present; in extracellular space enveloped "dense microbodies" are scattered among virions. The peculiar envelopment of CMV capsids, not yet described in the literature, is discussed and the typical ultrastructural cytopathology of CMV infected cells is indicated as an useful tool in diagnostic virology.