Aging and diethylstilbestrol-induced aneuploidy in male germ cells: a transgenic mouse model

The incidence of aneuploidy in male germ cells was evaluated by analyzing extra marker chromosome(s) signal(s) in round and/or hook spermatids of transgenic mice. Two types of transgenic mice were used as models. The inserted foreign DNA (lambda-gt10LacZ shuttle vector and/or pSVc-myc plasmid) was located at the middle of the long arms of chromosome 2 (lambda DNA) and/or chromosome 8 (c-myc). The number of marker chromosomes present could easily be detected after fluorescence in situ hybridization (FISH) in testicular cells. The frequency of spontaneous aneuploidy of chromosome 2 was similar in round spermatids of lambda and lambda-myc mice. Differential involvement of chromosomes 2 and 8 was observed in both round and hook spermatids. The frequency of spontaneous aneuploidy in round spermatids was higher than that in hook spermatids. The frequency of aneuploidy of marker chromosomes was significantly higher in older mice (2 years old) than in younger ones. Diethylstilbestrol (DES)-induced aneuploidy was dose dependent, and was not influenced by the stage at which germ cells were treated with DES. These results demonstrate the usefulness of a transgenic mouse model for the study of aneuploidy in germ cells.