vicia faba root tip cells were treated for short periods with tritiated thymidine , either immediately before or after exposure of roots to x-rays , and autoradiograph preparations were analysed in an attempt to test the hypothesis that chromatid type ( b ' ) aberrations are induced only in those chromosome regions that have synthesized dna prior to x-irradiation , whereas chromosome type ( b '' ) aberrations are induced only in unduplicated chromosome regions .
C0007634
cells
C0008545
chromatid