Sensitivity of oocytes in adult mice in the low-dose region

Based on reproductive performance recorded through 10 consecutive oestruses after whole-body X-irradiation, the hormonal influences of the oestrus cycle on radiosensitivity of oocytes in various stages of maturation have been investigated in inbred Swiss mice. Four groups of female mice, 10 batches per group, selected in oestrus heat and given 40 R X-rays at 24, 48, 72 and 96 h, respectively, were evaluated for reproductive efficiency in 10 subsequent oestrus cycles. Total implantation, number of live implants and post-implantation losses scored in 1-10 matings were used to measure the radiosensitivity of various stages of oocyte development. An unirradiated group served as control for the studies. The studies show that irradiation of a female during a given time in the oestrus cycle has profound influence on subsequent reproductive performance viz. litter size, indicidence of dominant lethals (post-implantation) and degree of sterility induced. (author)