urinary bladder 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] AAO:0000623 Anatomical structure which consists of a membranous sac used to temporarily store urine until it is excreted from the body.[AAO] BTO:0001418 CALOHA:TS-1090 EFO:0000290 EHDAA2:0000174 EHDAA:9328 EMAPA:18321 EV:0100098 FMA:15900 GAID:0000004 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] MA:0000380 MAT:0000122 MESH:A05.810.161 MIAA:0000122 OpenCyc:Mx4rvVjMmZwpEbGdrcN5Y29ycA UBERON:0001255 UMLS:C0005682 VHOG:0000740 XAO:0000154 bladder distensible musculomembranous organ situated in the anterior part of the pelvic cavity in which urine collects before excretion[MP]. galen:UrinaryBladder uberon urocyst vesica vesica urinaria vesical viscus mesoderm-derived structure bladder organ