[Thiophosphamide induction of chromosome disorders in the spermatogonia of 101/HY, TPS/Y and CBA/LacY inbred mouse strains].

The sensitivity of spermatogonia of 101, TPS and CBA inbred mice to induction of chromosome damages by thiophosphamide (thioTEPA) was studied. With respect to sensitivity of bone marrow cells, these strains were ranked as follows: TPS greater than 101 greater than CBA. When used at the dose 2.25 mg/kg i/p thioTEPA induced chromosome damages in 11.4, 11.6 and 6.0% of spermatogonia of TPS, 101 and CBA mice, respectively. Thus, selection which increased sensitivity of bone marrow cells of TPS mice poorly affected germ cells. To obtain more correct estimations of genetically determined mouse strain sensitivity to chemical mutagens, the estimations should be based on frequencies of induced mutations in germ cells. The spectrum of mutations in spermatogonia differs from that in bone marrow cells: the frequencies of isochromatid breaks and symmetrical chromatid exchanges are higher in spermatogonia. This can be due to close situation of homologous chromosomes in interphase nuclei of spermatogonia.