Murine spermatogonial regeneration after exposure to either X-rays or 15 MeV neutrons.

The long-term regeneration of the seminiferous epithelium after irradiation with 15 MeV neutrons was studied in the mouse on a comparative basis; 150 kV X-rays were used as reference-radiation. The mice received total-body exposures at matched doses. The spermatogonial Regeneration Index (RI) was scored from stained paraffin-sections of testes which were obtained after periodic sacrifice. A biphasic pattern of regeneration was recorded. Dose-independent and dose-dependent effects have been indicated. The radiobiological implications are discussed on a cellular basis.