Chromatid-type aberration is structural chromosome damage expressed as breakage of single chromatids or breakage and reunion between chromatids.
Chromosome-type aberration is structural chromosome damage expressed as breakage, or breakage and reunion, of both chromatids at an identical site.
Endoreduplication is a process in which after an S period of DNA replication, the nucleus does not go into mitosis but starts another S period. The result is chromosomes with 4, 8, 16,...chromatids.
Gap is an achromatic lesion smaller than the width of one chromatid, and with minimum misalignment of the chromatid(s).
Mitotic index is the ratio of cells in metaphase divided by the total number of cells observed in a population of cells; an indication of the degree of proliferation of that population.
Numerical aberration is a change in the number of chromosomes from the normal number characteristic of the cells utilized.
Polyploidy is a multiple of the haploid chromosome number (n) other than the diploid number (i.e., 3n, 4n, and so on).
Structural aberration is a change in chromosome structure detectable by microscopic examination of the metaphase stage of cell division, observed as deletions and fragments, intrachanges, and interchanges.
Metabolic activation condition | Chemical | CAS number |
Absence of exogenous metabolic activation | Methyl methanesulfonate | [66-27-3] |
Ethyl methanesulfonate | [62-50-0] | |
Ethylnitrosourea | [759-73-9] | |
Mitomycin C | [50-07-7] | |
4-Nitroquinoline-N-Oxide | [56-57-5] | |
Presence of exogenous metabolic activation | Benzo(a)pyrene | [50-32-8] |
Cyclophosphamide (monohydrate) | [50-18-0] ([6055-19-2]) |
40 C.F.R. §799.9537