<prompt> Trigone of Urinary Bladder develops from ?MesodermEctodermEndoderm of urachusEndoderm of urogenital sinus  <response>: Trigone is derived from mesoderm although bladder is endodermal in origin. Intermediate mesoderm forms the Genito urinary system. Endoderm forms the urogenital sinus which forms urinary bladder and urethra. 