Structure and function of blood-testis barrier and its role in damages induced by environmental contaminants

The blood-testis barrier (BTB) is a unique ultrastructure in adult mammals’ testis, which creates a unique microenvironment for normal spermatogenesis. Knowing the BTB mechanisms of actions can be used to reveals new targets for male contraceptive development. Meanwhile, understanding the molecular mechanisms of some BTB disruptors  such as cadmium and bisphenol-A not only provide approaches to manage toxicant-induced reproductive dysfunctions but it also illustrates new candidates molecules for contraceptive developments. The BTB is constituted by coexisting tight junctions (TJ), basal ectoplasmic specializations (basal ES), desmosomes and gap junctions between adjacent Sertoli cells. Some of the junctional proteins function as structural proteins of BTB and some other have regulatory roles. Studies have shown that male fertility can be impaired by various toxicants. Exposure of men to several environmental toxicants is reported to be associated with reduced sperm counts, poor semen quality, and infertility in addition to their effects to induce cancer and other pathological conditions. Some of them (cadmium, bisphenol A, phthalates, perfluorooctanoic acid) are known to exert their effects by targeting junctions in the blood -testis barrier. In this review, we will summarize the findings on the BTB structure and function as well as environmental pollutant-induced testicular injuries in men, such as BTB disruption.