A method for analysing sister-chromatid exchange in mouse preimplantation embryos.

Analysis of sister-chromatid exchange (SCE) has been shown to be a sensitive and reproducible method for detecting the action of mutagens and carcinogens. We have succeeded in establishing a reliable technique which allows to perform SCE in preimplantation embryos in order to make the pre-uterine stages of development accessible to routine detection of DNA damage. Using the mouse strain and technique described, approximately 30-40% of mice will mate successfully after synchronization and spontaneous ovulation. From 3 pregnant females, about 30 four- to eight-cell embryos will be obtained, representing one experimental group providing approximately 50-80 two-S-phase labelled metaphases with a SCE frequency baseline below 6 exchanges.