Embryogenesis of the hymen and caudal end of the vagina deduced from uterovaginal anomalies

Abstract

The morphogenesis of the caudal end of the vagina and hymen is controversial amongst embryologists. The urogenital sinus alone or in combination with the mullerian ducts, the wolffian ducts, or all three have been claimed to be the precursors of these organs. We describe two examples of imperforate hymen in one unit of a duplex vagina associated with ipsilateral ureterorenal anomalies that lend light to the controversy. The imperforate hymen occurred on the same side as the ureteric anomaly, indicating that the combined anomaly is derived from a deficit in a common denominator, the ipsilateral wolffian duct. The migration of the wolffian duct stopped short of the urogenital sinus, affected the development of the ureteric bud, and led to defective canalisation of the vaginal plate and the imperforate hymen. By inference, normal hymen formation is also mediated by the wolffian duct and is derived from the vaginal bulbs of urogenital sinus origin externally and the mullerian ducts internally; the vagina is also of mullerian origin. Once the normal hymen perforates, there may be intermingling of the sinus and ductal epithelia.