Complex sentence: 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.
Split into simpler sentences: The sinovaginal bulb is a transitional structure in the development of female genitalia. It is one of a pair of endodermal outgrowths of the urogenital sinus, which later fuse to form the lower part of the vagina.