part of part of in taxon develops from develops from contributes to morphology of Vertebrata <vertebrates> embryonic cloaca primitive urogenital sinus http://upload.wikimedia.org/wikipedia/commons/6/6d/Gray1109.png NCIT:C34322 Wikipedia:Definitive_urogenital_sinus EHDAA:5029 VHOG:0000414 fetal UGS EHDAA2:0004060 sinus urogenitalis UBERON:0000164 the term 'urogenital sinus' may refer to the primitive urogenital sinus present as a transient developmental structure in most mammals or it may refer to a condition in which an unseptated cloaca persists in animals longer than normal UGS In mammals the lowly monotremes still have a cloaca. Higher types have done away with this structure and have a separate anal outlet for the rectum. The monotreme cloaca shows the initiation of this subdivision. The cloaca has such includes only the distal part, roughly comparable to the proctodeum. The more proximal part is divided into (1) a large dorsal passage into which the intestine opens, the coprodeum, and (2) a ventral portion, the urodeum with which the bladder connects. (...) the development of the placental mammals recapitulates in many respects the phylogenetic story. In the sexually indifferent stage of placental mammal there is a cloaca. While the indifferent stage still persists, a septum develops, and extends out to the closing membrane. This divides the cloaca into two chambers: a coprodeum continuous with the gut above, and a urodeum or urogenital sinus below.[well established][VHOG] EMAPA:17379 UMLS:C0231057 urogenital sinus SCTID:50961009 The ventral part of the cloaca after its separation from the rectum, giving rise to the lower part of the bladder in both sexes, to the prostatic portion of the male urethra, and to the urethra and vestibule in the female. [TFD][VHOG] The ventral part of the cloaca remaining after septation of the rectum, which further develops into part of the bladder, part of the prostatic part of the male urethra and the urethra and vestibule in females. EHDAA:5919 embryonic structure intermediate mesoderm