Female ductal system

If the two paramesonephric ducts fail to fuse properly in their caudal longitudinal portion (primordium uterovaginale), there are several degrees of doubling of uterus and vagina which may occur.

-Uterus arcuatus:The fundus is slightly indented in the middle.
-Uterus bicornis: The uterus develops two horns, which end into a single vagina.
-Double uterus and vagina: Development of two uteri and vaginae.

If the paramesonephric ducts do not grow sufficiently caudally, then the uterus will not form (uterine aplasia)
If the paramesonephric ducts fail to form channels or canalize incompletely during the fetal period, this condition will result in atresia of the cervix or atresia of the vagina.
Aplasia of the vagina is attributed to an absence of a vaginal primordium.