part_of part of part of develops_from develops from Aves primitive urogenital sinus urinary bladder Urinary:system.svg https://upload.wikimedia.org/wikipedia/commons/3/30/Urinary_system.svg NCIT:C12414 Anatomical structure which consists of a membranous sac used to temporarily store urine until it is excreted from the body.[AAO] urocyst bladder GAID:0000004 MESH:A05.810.161 MIAA:0000122 Distensible musculomembranous organ situated in the anterior part of the pelvic cavity in which urine collects before excretion[MP]. Wikipedia:Urinary_bladder CALOHA:TS-1090 XAO:0000154 MA:0000380 OpenCyc:Mx4rvVjMmZwpEbGdrcN5Y29ycA uberon EV:0100098 vesica EHDAA:9328 galen:UrinaryBladder EMAPA:18321 In tetrapods, the urinary bladder arises as an outpocketing of the cloaca. (...) The tetrapod urinary bladder appears first among amphibians and is present in Sphenodon, turtles, most lizards, ostriches among birds, and all mammals.[well established][VHOG] MAT:0000122 A saccular organ in which urine accumulates before discharge from the body. [Bemis_WE, Functional_Anatomy_of_the_Vertebrates:_An_Evolutionary_Perspective, Glossary_G-29, Grande_L, Liem_KF, Third_Edition_(2001)_Orlando_Fla.:_Harcourt_College_Publishers, Walker_WF][VHOG] SCTID:302512001 UMLS:C0005682 EFO:0000290 UBERON:0001255 vesical AAO:0000623 BTO:0001418 VHOG:0000740 vesica urinaria FMA:15900 EHDAA2:0000174 The urinary bladder evolved in tetrapods. Birds to not possess a true urinary bladder, although Palaeognathae have an undifferentiated cloacal outpocketing that serves a similar function[https://github.com/obophenotype/uberon/issues/454] lower urinary tract viscus mesoderm-derived structure bladder organ