Stress-induced blocking of cell division in the colchicine arrest technique.

Previous studies have shown that procedures commonly used in studies of cell population kinetics in laboratory animals cause a transient block of the entrance of cells into mitosis. The purpose of the present study was, therefore, to examine whether the handling of animals in conjunction with the administration of colchicine affects the results obtained by the metaphase arrest technique. Groups of rats were injected with colchicine or saline at 1300 h and sacrificed at regular intervals during the following 140 min. Histological sections of the palatal mucosa were produced and the number of metaphases was assessed in the epithelium. In both the saline-treated and colchicine-treated groups the numbers of metaphases decreased immediately after injection and reached a minimum within 30 min. After that time a transient increase was observed in the saline group, whereas the number of metaphases in the colchicine-treated group increased continuously during the experimental period. These results indicate that colchicine takes effect after a delay period of 30 min and that the handling procedures in conjunction with the administration of colchicine provoke a transient block of the entry of cells into mitosis. The second part of the study was designed in such a way that the number of metaphases collected during a 2 h period under the influence of stress induced by injection of colchicine could be compared with the number of metaphases collected during the same time period without the influence of stress.(ABSTRACT TRUNCATED AT 250 WORDS)