INTRODUCTION

The testis performs two main functions that are largely complimentary, namely the production of spermatozoa and the production of hormones, principally testosterone. Any perturbations of either of these activities will result 1n reduced fertility. Generally, damage to testicular function can result from either Inhibition of the overall hormonal controlling mechanisms at the hypothalamic - pituitary or testicular level, or by direct action at the testicular cell level. Chemicals and drugs can exert their toxic effects via one or both of these mechanisms.

A number of morphological and functional parameters are employed to assess toxic effects on male reproduction, however the conventional methods used are mainly Involved with the overall controlling mechanisms, for example blood hormonal measurements, sperm analysis and fertility profiles. Histopathology and biochemistry provide an Insight Into events at the testicular level, but there 1s a need for a further reliable and fast method which will provide more detailed Information of events within the testis.

The testes consist of the seminiferous tubules, containing Sertoli cells and germ cells Involved 1n spermatogenesis (which make up over 90% of the testicular mass) and Interstitial Leydig cells (Figure 1). The endocrine control of spermatogenesis 1s very complex (Setchell, 1978; di Zarega and Shervis, 1981) Involving hormones from the pituitary (systemic) and Intragonadal hormones operating at a local level (paracrine) (Figure 2).