Hyperthermia induced dissociation of the X-Y bivalent in mice

The mutagenic potential of hyperthermia was examined employing a spermatocyte test on males heat stressed continuously for 2, 3. or 5 days. Stress conditions were 35 +/- 1 degrees C and 65 +/- 3% relative humidity. Males were sacrificed and meiotic preparations made from the testes at various intervals following removal from the stress environment. In this way, chromosome damage could be monitored in all premeiotic and early prophase I stages of spermatogenesis. Results of this study revealed a significant increase in the incidence of X and Y univalents at metaphase I. The significance of this finding is discussed.