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 Müllerian ducts typically regress due to the influence of testosterone and Müllerian inhibiting substance, which are produced by the developing testes. This regression prevents the formation of female reproductive structures, allowing for the development of male reproductive organs from the Wolffian ducts.