Structure:

The paramesonephric (Müllerian) ducts are paired embryological ducts that arise as invaginations of the coelomic epithelium along the lateral aspects of the urogenital ridges.[1,2] During early development, they run parallel to, and slightly lateral to, the mesonephric (Wolffian) ducts.  

Each paramesonephric duct is classically divided into three main segments:  

1. Cranial (Tubal) Part: contributes to the formation of the uterine tubes 

2. Intermediate (Uterine) Part: fuses with its contralateral counterpart in the midline to form the uterus 

3. Caudal (Vaginal) Part: contributes to the superior portion of the vagina.[1] 

Initially, the paramesonephric ducts lie dorsal to the mesonephric ducts. As development progresses, their caudal portions migrate medially and fuse to form a single uterovaginal canal.[3] 

Function:

In the genotypic female embryo, the paramesonephric ducts give rise to the majority of the internal reproductive organs, including the uterine tubes, uterus, cervix, and the upper portion of the vagina.[1] Abnormal development, fusion, or resorption of these ducts can result in paramesonephric duct anomalies, such as bicornuate uterus, septate uterus, or Müllerian agenesis (Mayer‐Rokitansky‐Küster‐Hauser syndrome). In the genotypic male embryo, these ducts regress under the influence of anti-Müllerian hormone (AMH) secreted by Sertoli cells. Failure of this regression results in persistent Müllerian duct syndrome, a condition characterized by retention of Müllerian derivatives in individuals with otherwise typical male development.[2]