![]() ![]() This discovery opened the door to numerous investigations into the long-term effects of developmental exposure to estrogenic compounds on male reproduction, an inquiry that continues today. The potential importance of estrogen during development of the male reproductive system was made popular by the report that diethylstilbestrol (DES) treatment during pregnancy induced cryptorchidism and epididymal cysts in male mice. ![]() However, it was clear from subsequent publications that most scientists did not consider estrogen to be a major steroid hormone in the male reproductive tract, in the adult. During the 1970's, the prediction of an estrogen receptor in testis and epididymis became a reality as estradiol binding was discovered. Reference to estrogen production by the testis was more of a curiosity at first, as efforts were made to determine the various metabolites of testosterone being produced. ![]() Thus, during the formative years of reproductive biology as a discipline it was suggested that estrogen might be important in the male however, even in the early 1990's many scientists considered estrogen receptor presence in the adult male reproductive tract to be a remnant from the indifferent sex stage of embryological differentiation. It was also known in the 1930's and 40's that developmental exposure to high doses of estrogens could induce malformation of the male reproductive tract. It was known as early as the 1930's that the developing testis was responsive to the "female" hormone, also reviewed by ]. Thus, we conclude that estrogen or its α-receptor is an absolute necessity for fertility in the male. In addition to this primary regulation of luminal fluid and ion transport, estrogen is also responsible for maintaining a differentiated epithelial morphology. Disruption of the α-receptor, either in the knockout (αERKO) or by treatment with a pure antiestrogen, results in dilution of cauda epididymal sperm, disruption of sperm morphology, inhibition of sodium transport and subsequent water reabsorption, increased secretion of Cl -, and eventual decreased fertility. Estrogen receptors are abundant in the efferent ductule epithelium, where their primary function is to regulate the expression of proteins involved in fluid reabsorption. However, estrogen receptor-α is reported absent in the testis of a few species, including man. Estrogen receptors are present in the testis, efferent ductules and epididymis of most species. In the adult testis, estrogen is synthesized by Leydig cells and the germ cells, producing a relatively high concentration in rete testis fluid. It was known as early as the 1930's that developmental exposure to a high dose of estrogen causes malformation of the male reproductive tract, but the early formative years of reproductive biology as a discipline did not recognize the importance of estrogen in regulating the normal function of the adult male reproductive tract. Both hormones are important in both sexes. Testosterone and estrogen are no longer considered male only and female only hormones. ![]()
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