Fertility of rats with artificial oligozoospermia.

Three different methods to obtain "oligospermic" rats were investigated. (1) Surgical reduction of the amount of tubular tissue diminished the number of spermatozoa present in the epididymis, but the animals were not infertile as long as they were able to ejaculate (32/33 rats). (2) Treatment with oestradiol benzoate on the 5th day after birth caused only slight reduction of spermatogenesis and most of these animals were fertile. (3) X-irradiation of 20 male rats 1-3 days before birth yielded 8 rats with severely diminished spermatogenesis which were infertile although they did mate and spermatozoa were observed in vaginal smears. This suggests that 'spotty' spermatogenesis in the testes of these animals (as in infertile men) results in spermatozoa of diminished fertility.