Radiosensitivity of Oogonia and Oocytes in the Foetal Rat

Abstract

Pregnant rats were exposed to doses of 25 to 2 x 100 r of X-rays at varying times between the 13th and the 20th days after insemination. Female offspring were killed at 25 days post partum, and the number of oocytes was estimated from serial sections of the ovaries. The population of oocytes in the irradiated ovaries was found to depend both on the dose of X-rays administered and on foetal age at the time of exposure. The period of maximum radiosensitivity, which occurred on the 15th day of gestation, was found to coincide with a high rate of mitotic division of oogonia.