Chronic irradiation of gonad tissue of the male rat

The effects of chronically irradiating rats' testes with daily gamma radiation doses of (1.4 - 8.6) x 10-2 Gy for 71-140 days were studied. After about 30 days irradiation, the testes weights decrease and level off at about 75 days. Irradiation also caused the germ cells in the seminiferous tubules to disappear progressively, completely when the dose exceeded 6 x 10-2 Gy/day and partially with the lower doses. At doses below 6 x 10-2 Gy/day, there was also a delay in the spermatogenesis cycle with the spermatogonia and spermatocytes appearing to reach a new equilibrium, the level of which depended on the dose. (U.K.)