Stage-sensitivity and dose-response study after gamma-irradiation of mouse primary spermatocytes.

The sensitivity pattern for X-ray-induced chromatid aberrations was analysed in primary spermatocytes irradiated at 1 to 11 days diakinesis-metaphase I of meiosis. Using a dose of 300 R (60 R/min) of gamma-rays zygotene (day 9) was found to be the most sensitive and leptotene (day 11) the most insensitive stage. The dose-response to gamma-ray-induced aberrations was evaluated in cells irradiated zygotene. Both the yields of rearrangement as well as the yields of fragments gave a best fit to a quadratic model.