The Müllerian duct is a pair of embryonic structures that play a crucial role in the development of the female reproductive system. During early fetal development, these ducts form and eventually develop into key reproductive organs, including the fallopian tubes, uterus, and upper two-thirds of the vagina. In males, the presence of testosterone leads to the regression of the Müllerian ducts, preventing the formation of female reproductive structures. This process is essential for sexual differentiation, ensuring that males develop male reproductive organs while females retain the Müllerian ducts to form their reproductive anatomy.