Study on radiosensitivity of germ cells of a male killfish during the non-breeding season

Oryzias Latipes received systemic irradiation of x-ray (0, 100, 250, 500, 1000, 4000 rads) during the non-breeding season (winter), after which they were bred and observed at 250C. The group which had received 100 rads showed the retardation of the weight of testicle, and the group which had received the irradiation of more than 250 rads showed its atrophy. However, the 100 rads-irradiated group recovered to the level of control group 30 days later, and even the 500 and 1000 rads-irradiated groups recovered to the level 60 days later. Pyknosis appeared remarkably in the spermiogonia and immature spermiocytes of the subjects (Oryzias Latipes) which received the irradiation of more than 500 rads. Spermiogonia (Ia) were not destructed by irradiation of 1000 rads, and they were proliferated in the recovery stage. Some of spermiogonia (Ib) became extinct by irradiation of 100 rads, and its fission was influenced. Decreased differentiation of spermiogonium to spermiocyte was observed clearly by 100 rads. Decreased uptake of 3H-Thymidine was observed by irradiation of 1000 rads (one day later). The role of pituitary gland for the fission of spermiogonium and its differentiation into spermiocyte was discussed. (Takeda, Y.)