Microtubule-organizing centres in binucleate cells and homosynkaryons

Immunofluorescence studies showed that most binucleate Vero cells formed by virus-induced fusion or by inhibition of cytokinesis had a single microtubule-organizing centre (MTOC) when examined during the reassembly of microtubules after chilling, but two or more organizing centres when examined after exposure to colcemid. These findings suggest that although binucleate cells initially contain more MTOC than mononucleate cells, the extra MTOC are normally aggregated, so that the number of MTOC in binucleate cells tends to be reduced very quickly to that in mononucleate cells.