Xenoestrogen
Xenoestrogens are clinically significant because they can mimic the effects of endogenous estrogen and thus have been implicated in precocious puberty and other disorders of the reproductive system.
Estrogen (medication)
High-dose estrogen therapy is effective in suppressing spermatogenesis and fertility in men, and hence as a male contraceptive. It works both by strongly suppressing gonadotropin secretion and gonadal testosterone production and via direct effects on the testes. After a sufficient course of therapy, only Sertoli cells and spermatogonia remain in the seminiferous tubules of the testes, with a variety of other testicular abnormalities observable. The use of estrogens for contraception in men is precluded by major side effects such as sexual dysfunction, feminization, gynecomastia, and metabolic changes. In addition, there is evidence that with long-term therapy, fertility and gonadal sex hormone production in men may not return following discontinuation of high-dose estrogen therapy.