Effect on gonadotrophin secretion of blockage of the ductuli efferentes in the normal and androgen-deprived rat

Serum LH and FSH concentrations were measured in adult male rats. Blockage of the ductuli efferentes by surgical ligation or treatment with the anti-fertility drug alpha-chlorohydrin did not produce any changes in serum LH or androgen-dependent organ weights. Serum FSH in both groups was significantly raised by 4 days after treatment and remained so throughout most of the experimental period (42 days) but did not attain the values obtained in castrates. The gonadotrophin changes were accompanied by an initial increase in the weight and turgidity of the testes which then became flaccid and atrophied. These changes were similar but not identical after both treatments. Androgen secretion was impaired in adult rats treated with ethylene dimethane sulphonate; serum LH values were similar to those of 14-day castrates, and serum FSH was also elevated but not to the level found in the castrates. Ligation of the ductuli efferentes did not produce any further changes in concentrations of either hormone in spite of the retention of the testicular products within the testes as reflected by an increase in weight. The results are consistent with the view that changes in serum FSH after blockage of the ductuli efferentes are related to disturbances in the production of inhibin from the seminiferous epithelium rather than retention of inhibin with the testicular tubules.