[Electron microscopy studies on proliferation of foot-and-mouth disease virus in cell cultures. I. Morphologic changes in cell nucleus].

The first morphological indication of FMD infection of a cell culture was in the nucleus. Components of nucleoli became segregated and were finally present only as remnants. It was not possible to distinguish different stages of segregation, as in the case of entero-virus infections, because of the rapidity of FMD virus proliferation. Following changes in nucleoli there was margination of chromatin. Particularly striking was an increase in interchromatin granules. Changes in the nuclear membrane seemed to facilitate the transfer of nuclear material to the cytoplasm. Strongly pronounced dilatation of the peri-nuclear cleft, like that seen in aphthae and other tissues, were rarely visible in infected cell cultures.