EFFECTS OF SEX HORMONES ON GERMINAL CELLS OF THE RAT TESTIS: A RATIONALE FOR THE USE OF PROGESTIN AND ANDROGEN COMBINATIONS IN THE CONTROL OF MALE FERTILITY

Summary. A biochemical test is described which reveals metabolic changes in isolated non-flagellate germinal cells of the rat testis within 4 days of treatment of the animals with sex hormones. By means of this test, a number of progestational compounds were surveyed and their minimum effective dose levels determined. Long-term treatment of male rats (100 to 400 g) with a progestin (0·5 to 2·0 mg/day) caused atrophy of the secondary sex glands and decreased spermatogenesis with loss of libido. When atrophy of accessory sex glands was prevented by concurrent administration of testosterone (10 to 100 μg/day), the animals continued to mate although the sperm count in the epididymis was severely depressed. All sex organs returned to normal after cessation of the treatment. These findings provide the background for the development of a male contraceptive combining a progestin with an androgen.