[Effect of methotrexate and actinomycin D on the frequency and ratio of early mitotic cells]

Different methods for obtaining early mitotic chromosomes have been comparatively analyzed. Lymphocyte cultures have been treated with methotrexate, actinomycin-D and with a combination of both agents. It is shown that a high rate of chromosomes in prophase, prometaphase and mid-metaphase can be achieved by the combined methotrexate and actinomycin-D treatment of the lymphocyte culture. Methotrexate treatment of cultures is preferable to obtain the great number of early metaphase chromosomes.