For the year 1980-81, research will concentrate on the in vivo effects of mutagens and mitotic poisons. Since this project is designed to work out assay systems instead of testing unknown compounds, we plan to use unknown mutagens for working out the protocols. Two tissues, the bone marrow (somatic cells) and testis (germline) will be examined in all cases. We plan to use the second meiotic division to estimate the extent of aneuploidy induced in the first meiotric division. Animals to be used: laboratory mice and Chinese hamsters.