A simplified procedure for the observation in situ of chromosome aberrations or sister chromatid exchanges and the estimation of the mitotic index in mammalian monolayer cell cultures.

Chinese hamster V-79 cells are widely used in short term screening for potential physical or chemical mutagens of the environment. A simplified version of the standard Giemsa protocol of Moorhead and the Feulgen plus Giemsa protocol of Wolff and Perry is given which permits the observations in situ of chromosome aberrations or sister chromatid exchanges and the estimation of the mitotic index in the Petri dishes used for the culture of the V-79 cells.