human peripheral blood lymphocytes were exposed in vitro to a series of graded concentrations of ethyl methanesulphonate ( ems ) or n-ethyl-n-nitrosourea ( enu ) or mitomycin c ( mmc ) to : ( a ) estimate the frequency of thioguanine-resistant ( tgr ) cells using the t-cell cloning technique , ( b ) examine the induction of sister-chromatid exchanges ( sces ) by these chemicals in the lymphocytes of the same blood sample used to study the tgr cells , and ( c ) assess the nature of correlations between these two biological end-points .
C0037211
sister-chromatid exchanges
C0007634
cells