The paramesonephric ducts develop in the female because of a lack of anti-mullerian hormone. These paramesonephric ducts form the majority of the female reproductive tract. The fallopian tubes develop from the upper unfused portions of the ducts while the lower fused portion of the ducts forms a uterovaginal primordium which gives rise to the uterus and vagina.
The sinovaginal bulbs form when the uterovaginal primordium contacts the urogenital sinus. If these bulbs do not form, agenesis of the vagina occurs. The bulbs later fuse. The cells of the fused bulbs then undergo apoptosis to form the lumen of the vagina.
