The testicular toxicity of several chemicals was investigated using laboratory rats and Beagle dogs. Testicular measurements, assays of circulating pituitary-testicular hormones, semen examinations and quantitative histometric studies of spermatogenesis were used, when appropriate, to complement the results of organ weight analyses and conventional histological examinations. Variations in testicular function may be encountered as a result of differences due to species, strain, age, diurnal and seasonal rhythms, methods of sampling and spontaneous pathological changes in the male reproductive organs. These factors should be considered when assessing the importance of testicular changes found after administering large doses of chemicals to experimental animals. Compounds were administered to rats and dogs which affected LH and prolactin concentrations as a result of pharmacological overdosage. Similar hormonal changes were detected for both species, but differing degrees of morphological change were encountered in the testes and secondary sex organs. The dog appeared to be more susceptible to effects on the hormonal control of spermatogenesis than was the rat. Hormonally mediated suppression of spermatogenesis was shown to be reversible within two spermatogenic cycles following withdrawal of the test compounds. Toxicological assessment of some chemical actions on the seminiferous epithelium of rats and dogs was attempted. It was possible to obtain useful information for compounds having a primary antisperm-atogenic action, and the Beagle dog seems to be a suitable non-rodent species for the toxicological study of these compounds. The methods employed for these investigations were less useful for assessing the safety of domestic or agricultural chemicals, which affected the seminiferous epithelium when administered at excessive dosages only.
|Date of Award||1980|