Murine bone marrow culture system for cytogenetic analysis.

A mouse bone marrow culture system for examining genotoxicity of agents by first exposing animals in vivo then growing cells in vitro is presented. This assay can also be used for in vitro and/or for the in vivo and in vitro comparative cytogenetic studies. The protocol involves culturing of approximately 1,000,000 nucleated cells obtained from mice tibia and femora in 5 ml of Ham's F-12 medium containing 20% fetal bovine serum, 10% whole uterus extract from pregnant mice and 1% penicillin-streptomycin. The use of flasks and mouse uterus extract for culturing are important steps for higher mitotic yield. The addition of 20 microM BrdU for 24 h helps in the differentiation of sister chromatids for sister-chromatid exchange (SCE) analysis. Cyclophosphamide, given to mice through intraperitoneal injection, induced significant dose-related SCEs in culture. Trinitrofluorenone, a direct-acting mutagen, caused dose-related SCEs in in vitro bone marrow cell culture.