Summary
The effects of heat on the radiosensitivity of primordial germ cells at the quiescent stage in the fish Oryzias latipes were studied. The results show: (1) heat preceding but not following irradiation induced radioresistance which was reflected by improved survival; (2) its magnitude was a function of the heating time before irradiation; (3) improved germ-cell survival did not change with time for up to at least 4 hours after heat treatment at 41°C for 30 min; (4) this resistance was more prominently expressed in the subsequent course of proliferation of female germ cells than in the non-proliferating male germ cells.
In conclusion, heat induced radiation resistance in primordial germ cells of the female at the quiescent stage; this probably allows the cells subsequently to escape reproductive death.