Radiation Effects from Prenatal Exposure to Accelerated Heavy Ions on Testicular Development and Reproductivity in Rats

Effects of in utero exposure of male fetal Wistar rats on embryonic day 15 to accelerated heavy ions on the fetal gonads, postnatal testicular development and reproductivity were investigated in a dose range from 0.1 Gy to 2.0 Gy. The effects of X-rays at 200 kVp were studied for comparison. A dose of 2.0 Gy caused 100%, 18%, and 12% preweaning mortality by irradiations with neon ions, carbon ions and X-rays, respectively. For neon ions, a dose as low as 0.1 Gy led to significant alterations to such as preweaning mortality, testis weight, and ratio of testis weight to body weight. For carbon ions or X rays, a dose of 0.5 Gy or more was usually needed to induce a marked effect. Irradiation with 0.5 Gy or more, resulted in a dose-dependent induction of apoptosis in gonocytes, increased prenatal death, delayed accomplishment in testis descent, low testis weight, changed ratios of testis weight to body weight, and increased malformed testicular tubules. When the prenatal dose was at 1.0 Gy or 1.5 Gy, marked decrease in successful mating rates with the non-irradiated female was also scored in the prenatally irradiated male. On the other hand, a significant increase in prenatal death and preweaning mortality was observed in animals that were descended from the irradiated male receiving prenatally 0.5 Gy or more and the non-irradiated female. These findings indicated that fetal irradiations on embryonic day 15 generally induced markedly detrimental effect on fetal development, postnatal testicular maturation and reproductivity in male rats, which was a dose and LET-related event.