[The effect of UV microirradiation of the centrosome on cell behavior. I. The destruction of the mitotic spindle and disruption of cell division during irradiation in the metaphase].

A 5 second UV microirradiation of the centrosome during the early metaphase leads to a rapid (within 5 minutes) chromosome shift towards the normal pole and disorganizes the spindle. The later metaphase plate is also disorganized, chromosomes being situated chaotically in the central part of the cell. Numerous (up to 10 or more) microtubule convergence centers are observed instead of the spindle. 2-4 hours after the microirradiation some cells may enter cytotomy. The microirradiation of chromosomes and cytoplasm in similar and greater doses (exposure up to 15 seconds) did not lead to disorganization of the spindle and did not effect the normal completion of mitosis. Sometimes the 5 second microirradiation in the middle metaphase also blocked anaphase, but the microirradiation within the last 5 minutes of the metaphase always failed to block anaphase and normal completion of division.