| Budget Amount *help |
¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2015: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2014: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2013: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
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| Outline of Final Research Achievements |
The aim of this study was to investigate the effect of radiation dose rate and irradiation period on radiosensitivity of male germ cells in juvenile mice. When gonocytes (day 16.5 post-coitus) were exposed to γ-ray at 2 Gy with high dose-rate, testicular weight was reduced at 10 weeks of age and no spermatozoa were found in the epididymis, leading to sterility at reproductive age. Percentage of primary spermatocytes with multivalent chromosomes was high in the group of spermatogonial stem cells (day 11 post-partum) exposed to γ-ray with high dose-rate. When the first mitotic chromosomes of in vitro fertilized zygotes were analyzed, the incidence of spermatozoa with chromosomal aberrations in any irradiation group was similar to that of the control group. These results suggested that gonocyte of mice had relative high radiosensitivity and that the risk for spermatozoa with chromosomal aberrations at any irradiation age and radiation dose-rate did not increase.
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