The article presents the mechanism of action of estrogen and their importance for the proper reproduction male. In the male gonad , estrogens are produced by the Leydig cells and Sertoli and through successive stages gametogenicznych cells . Estrogen receptors are expressed in the testis, efferent ductules , epididymis , and prostate . Estrogens affect the male reproductive system indirectly by regulating the secretion of gonadotropins by the pituitary gland , and directly affecting the proliferation, maturation and function of Leydig cells and Sertoli and controlling division , differentiation, and survival of germ cells . Recent studies conducted in transgenic mice lacking estrogen receptor and aromatase provide conclusive evidence that estrogens and their receptors are necessary for the proper conduct of spermatogenesis and male fertility . Despite numerous studies conducted in animal models , cell cultures , and observation of patients with impaired synthesis of estrogen , many aspects of these hormones on male reproductive function still requires explanation.