Aneuploidy induction in mouse spermatocytes.

Assays for aneuploidy are being developed within a coordinated research program sponsored by the Commission of the European Communities. The 10 known and suspect spindle poisons colchicine (COL), econazole (EZ), chloral hydrate (CH), hydroquinone (HQ), diazepam (DZ), thiabendazole (TB), cadmium chloride (CD), pyrimethamine (PY), thimerosal (TM) and vinblastine (VBL) were tested for aneuploidy induction in male germ cells. Two different criteria were used for the evaluation of slides from testicular material of (102/El x C3H/El)F1 mice at different times (6, 14 and 22 h) after treatment with different doses of each of the test chemicals. Secondary spermatocytes of mice were evaluated by chromosome counting to determine the induction of hyperploidy. The proportions of spermatogonial mitoses, first and second meiotic metaphases were determined in order to recognize an effect of the test chemicals on testicular cell proliferation. COL, EZ, CH, HQ and VBL clearly increased the frequencies of hyperploid secondary spermatocytes which indicated non-disjunction induction during the first meiotic division. DZ and CD were less effective but significantly positive (P less than 0.05). Concomitantly, COL, EZ, CH, HQ, DZ, CD and VBL induced meiotic delay in primary and/or secondary spermatocytes. It is concluded that meiotic delay may be indicative for aneuploidy induction and the evaluation of changes in testicular cell proliferation described here could serve as a prescreen and partially substitute the time-consuming counting of metaphase chromosomes in secondary spermatocytes.