Spermatid micronucleus analyses of trichloroethylene and chloral hydrate effects in mice.

Mice were exposed by inhalation to trichloroethylene (TCE) or by i.p. injection to the TCE metabolite, chloral hydrate (CH). Early spermatids were analyzed for micronucleus (MN) frequency and the presence or absence of kinetochore(s) using fluorochrome-labeled anti-kinetochore antibodies. It was determined that 5 consecutive days of exposure to 5, 50 or 500 ppm TCE during preleptotene through early pachytene stages of meiotic cell development do not result in increased frequencies of spermatid MN. CH at 41, 83 or 165 mg/kg was positive for spermatid MN induction when treatments corresponded to spermatogonial stem cell or preleptotene spermatocyte stages of development; negative results were obtained after treatments of leptotene-zygotene or diakinesis-metaphase stages. The significantly increased levels of MN observed were invariably of the kinetochore-negative type.