The incidence of aneuploidy in male germ cells was evaluated by analyzing e
xtra marker chromosome(s) signal(s) in round and/or hook spermatids of tran
sgenic mice. Two types of transgenic mice were used as models. The inserted
foreign DNA (lambda-gt10LacZ shuttle vector and/or pSVc-myc plasmid) was l
ocated at the middle of the long arms of chromosome 2 (lambda DNA) and/or c
hromosome 8 (c-myc). The number of marker chromosomes present could easily
be detected after fluorescence in situ hybridization (FISH) in testicular c
ells. The frequency of spontaneous aneuploidy of chromosome 2 was similar i
n 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 tha
t in hook spermatids, The frequency of aneuploidy of marker chromosomes was
significantly higher in older mice (2 years old) than in younger ones. Die
thylstilbestrol (DES)-induced aneuploidy was dose dependent, and was not in
fluenced by the stage at which germ cells were treated with DES. These resu
lts demonstrate the usefulness of a transgenic mouse model for the study of
aneuploidy in germ cells.