The Radiosensitivity of Germ-cells at Various Stages of Ovarian Development

Summary

Female rats were exposed to 50 and 100 r x-rays on the 8th, 10th and 12th days of intra-uterine life, at birth and on the 2nd and 5th days after birth.

As judged by the survival of oocytes at the age of 25 days, germ-cells in the developing ovary undergo two periods of high radiosensitivity: the first at 15 days post coitum, when oogonial mitoses are frequent, and the second shortly after birth, when the oocytes attain the dictyate phase. The intervening period of relative refractoriness to radiation damage occurs while the oocytes undergo the prophase of meiosis.