The sinovaginal bulb is a transitional structure in the development of female genitalia, and is one of a pair of endodermal outgrowths of the urogenital sinus, which later fuse to form the lower part of the vagina.[1] [2] The lower third of the vagina is derived from the urogenital sinus.[3]
The hymen is formed from the same tissue as the sinovaginal bulb.[1]