Fetuses begin with two kinds of internal reproductive systems, one of them called Mullerian and the other Wolffian. In typical female development, the Wolffian structures disappear and the Mullerian structures form the uterus, Fallopian tubes, and upper part of the vagina. In typical male development, the Mullierian structures disappear and the Wolffian structures grow and develop into various male-typical parts, including the prostate and vas deferens.
If a male (46,XY) fetus has persistent Mullerian duct syndrome (PMDS), then as the name implies, his Mullerian structures will persist and grow rather than disappearing during development. The male with PMDS will develop the usual male structures internally and externally, but in addition, he will also develop some internal structures that are female-typical. These may include a uterus and Fallopian tubes. Sometimes this condition also involves failure of the testicles to descend (cryptorchidism).
Posted in: Specific Conditions