From week 12, the paramesonephric ducts develop more strongly. Each of them has an abdominal ostium at their place of origin that develops fimbriae at later stages. Three parts of the duct can be distinguished. The uterine tube develops from the cranial, longitudinal part; the intermediate, transversal part gives rise to the fundus and to a part of the uterine body; the caudal, longitudinal part becomes the uterovaginal primordium. The epithelial lining of the uterus originates from the paramesonephric duct, and the remainder of the lining from the surrounding mesenchyme. In a fetus measuring 60 mm in length, the epithelium proliferates in the region of the sinual tubercle. This proliferation extends cranially (vaginal plate) and increases the distance between the uterus and the urogenital sinus. This cord of tissue later forms a lumen, and in this way develops into the vagina. The distal end of the vagina shifts caudally along the urethra. However, it remains separated from the urogenital sinus by a thin layer of tissue (hymen).