ABSTRACT
The incidence of reproductive failure in the human population is relatively high with estimates that 7% of all newborns (200,000 of 3 million live births) in the US have birth defects each year. Information on the mechanism of action of these agents on the male reproductive system is scarce and is inferred mostly from mechanism studies in other tissues. Most of the agents listed in the tables cause reversible effects on male reproductive function; sterility and pathologic effects on the testis are rarely permanent with physical and chemical insult. Evidence exists for the presence of a permeability barrier in the testis. The distinctive composition of testicular fluid relative to blood plasma and the exclusion of radiolabeled compounds from seminiferous tubules suggest compartmentalization of the testis. The blood-testis barrier lies between the lumen of interstitial capillaries and the lumen of seminiferous tubules.
