Estrogen has always been considered the female hormone and testosterone the male hormone. However, estrogen's presence in the testis and deleterious effects of estrogen treatment during development have been known for nearly 90 years, long before estrogen receptors (ESRs) were discovered. Eventually it was learned that testes actually synthesize high levels of estradiol (E2) and sequester high concentrations in the reproductive tract lumen, which seems contradictory to the overwhelming number of studies showing reproductive pathology following exogenous estrogen exposures. For too long, the developmental pathology of estrogen has dominated our thinking, even resulting in the “estrogen hypothesis” as related to the testicular dysgenesis syndrome. However, these early studies and the development of an Esr1 knockout mouse led to a deluge of research into estrogen's potential role in and disruption of development and function of the male reproductive system. What is new is that estrogen action in the male cannot be divorced from that of androgen. This paper presents what is known about components of the estrogen pathway, including its synthesis and target receptors, and the need to achieve a balance between androgen- and estrogen-action in male reproductive tract differentiation and adult functions. The review focuses on what is known regarding development of the male reproductive tract, from the rete testis to the vas deferens, and examines the expression of estrogen receptors and presence of aromatase in the male reproductive system, traces the evidence provided by estrogen-associated knockout and transgenic animal models and discusses the effects of fetal and postnatal exposures to estrogens. Hopefully, there will be enough here to stimulate discussions and new investigations of the androgen:estrogen balance that seems to be essential for development of the male reproductive tract.

雌激素一直被认为是女性荷尔蒙，睾酮是男性荷尔蒙。然而，在雌激素受体 (ESR) 被发现之前，近 90 年来，人们就知道睾丸中存在雌激素和雌激素治疗在发育过程中的有害影响。最终了解到，睾丸实际上合成了高水平的雌二醇 (E2) 并在生殖道腔中隔离了高浓度，这似乎与绝大多数研究表明外源性雌激素暴露后的生殖病理学相矛盾。长期以来，雌激素的发育病理学一直主导着我们的思考，甚至​​产生了与睾丸发育不全综合征有关的“雌激素假说”。然而，这些早期研究和Esr1的开发基因敲除小鼠引发了大量关于雌激素在雄性生殖系统发育和功能中的潜在作用和破坏的研究。新的是，男性的雌激素作用不能与雄激素的作用分开。本文介绍了对雌激素途径成分的了解，包括其合成和靶受体，以及在雄性生殖道分化和成人功能中实现雄激素和雌激素作用之间平衡的必要性。该综述重点关注从睾丸网到输精管的男性生殖道发育的​​已知情况，并检查男性生殖系统中雌激素受体的表达和芳香酶的存在，追踪雌激素相关基因敲除和转基因动物模型提供的证据，并讨论胎儿和产后暴露于雌激素的影响。希望这里有足够的内容来激发对雄激素：雌激素平衡的讨论和新的调查，这似乎对男性生殖道的发育至关重要。