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The Müllerian, or paramesonephric, ducts are critical structures in the development of the internal genitalia of the female reproductive system. The first observation of this formation was by JP Müller in 1830. The Müllerian ducts ultimately form the uterine or fallopian tubes, uterus, cervix, and proximal third of the vagina in females. Initially, the Müllerian ducts are present in both sexes and appear as paired channels extending inferiorly along the lateral aspect of the embryo to the urogenital sinus at its sinus tubercle. These ducts typically regress in males under the influence of Anti-Müllerian Hormone (AMH), also known as Müllerian Inhibiting Substance (MIS), Müllerian Inhibiting Hormone (MIH), or Anti-Müllerian Factor (AMF). Anti-Müllerian hormone is produced by the Sertoli cells of the testes and inhibits the development of the female internal genitalia. Without the influence of AMH, the Müllerian or paramesonephric ducts develop in either sex into the uterus, uterine tubes, cervix, and the superior 1/3 of the vagina. The incipient development of the Müllerian ducts in both sexes and the subsequent development along a female path after sex determination are thought to be highly regulated by distinct signaling molecules and gene expression, including EMX2, HOXA13, PAX2, LIM1, and WNT. Disruption of these mechanisms can result in various developmental anomalies of the female internal genitalia, such as agenesis of the uterus or formation of a unicornuate, bicornuate, didelphic, septate, or arcuate uterus.[1][2]