Abstract
Summary
Formation of mitotic figures and micronuclei in a colchicine-treated human synovial cell line (McCoy) were quantitated at different times after treatment. After a lag period of 4 hours, mitotic figures increased in a roughly linear manner until the 12th hour. A rapid drop to control values by the 15th hour was correlated with the appearance of micronucleated cells. A second lag period of approximately 4 hours was followed by an apparently enhanced rate of formation of mitotic figures to the 30th hour after treatment. After this point their numbers gradually decreased so that at 72 hours virtually none was seen. Except for shifts induced by this second lag period, micronucleated cells continued to increase after the 12th hour at a more-or-less constant rate through the 30th hour. The micronucleated cells were terminal forms resulting from colchicine treatment except for a nearly constant fraction (10%) of polyploid giant cells which remained unchanged.
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