Effect of low doses of gamma-radiation on the steady-state spermatogenesis of mouse: a flow-cytometric study.

Radiation-induced perturbations in the steady-state spermatogenesis of mouse exposed to 0.05 to 2 Gy of 60Co gamma-radiation were studied at 7 to 70 days post-irradiation flow cytometrically. Five quantifiable populations viz: elongated spermatids (HC), round spermatids (1C), spermatogonia and other diploid cells (2C), spermatogonial cells synthesizing DNA (S-phase) and primary spermatocytes (4C) were identified in the sham-irradiated controls. Exposure of mice to different doses of radiation resulted in a significant decline in the total germ-cell transformation ratio (1C:2C) at 21 and 28 days post-irradiation as compared to the control group, except for the animals exposed to 0.05 Gy. The 1C:2C ratio is sub-divided into two components viz. 4C:2C and 1C:4C. The 4C:2C ratio decreased significantly on day 14 post-irradiation, except for 0.05 Gy where it was non-significant. Consequently, meiotic transformation (1C:4C) showed a significant increase on day 14 post-irradiation compared to the sham-irradiated control barring 0.05 Gy where the difference between the two groups was non-significant. The ratio of HC:1C (cell transformation during spermiogenesis) increased significantly at day 21 post-irradiation 0.2 to 2 Gy and between day 7 and 14 for 0.05 Gy as compared to the control group. It appears that a dose as low as 0.05 Gy radiation was able to cause the perturbations in the steady-state spermatogenesis of mouse and normalcy was not restored even up to 70 days post-irradiation at all exposure doses.