Urinary bladder develops from ?

Postallantoic pa of hind gut is the dilated endodermal cloaca, which is separated from the surface by cloacal mambrane.Urorectal septum divides endodermal cloacae into :-i) Anterior pa, known as primitive urogenital sinus, which develops into urinary bladder and urethra.ii) Posterior pa, known as primitive rectum, which gives rise to lower pa of rectum and upper pa of anal canal.