Fusion of XC cells by murine type-C viruses: cinematographic observations.

Continuous observations on the processes of multikaryon formation by purified murine type-C virus, produced by a line of murine myeloma cell cultures and Rauscher leukemia virus, were carried out by cinematography. The process first began by fusion of two mononucleated cells and additional cells continued to introduce their cytoplasm and nucleus one after another to give rise to multinucleated giant cells. These findings strongly suggested that the formation of multikaryons is due to a cellular fusion process and not to endomitosis.