MECHANISMS OF TESTICULAR TOXICITY

Abstract

This review focusses on the mechanisms of testicular toxicity, and the underlying requirement for a detailed understanding of the characteristics of the testis. Factors such as active mitosis, the presence of a blood-testis barrier, the spermatogenic cycle, and hormonal control, complicate the situation with regard to toxicity. However, the general mechanisms of testicular toxicity types can be classified as follows: 1) Direct-action against spermatogenic epithelia; 2) Hormonal indirect effects on spermatogenesis; 3) Direct or indirect mechanisms affecting sperms; 4) Circulatory disturbances affecting the testis; 5) Other miscellaneous actions. In the histological evaluation of testicular toxicity, histological patterns of toxic lesions induced by different model chemicals, categorized on the basis of their mechanisms of action, are very helpful. For typical examples are cyclophosphamide, nitrobenzene, ethane-1, 2-dimethanesulfonate, and cadmium chloride. Studies with these compounds have strongly suggested that early changes, rather than those occurring at late stages, are of particular assistance for understanding their mechanisms of action.