A common passage for fecal, urinary, and reproductive discharge in most lower vertebrates as well as the terminal end of the hindgut before division into rectum, bladder, and genital primordia in mammalian embryos. [TFD][VHOG]

Anatomical structure which is the common receptacle for the alimentary canal, Wolffian ducts, oviducts, and the bladder.[AAO]

A cloaca is apparently a primitive vertebrate feature because it occurs in most primitive gnathostomes and persists in the embryos of almost all vertebrates.[well established][VHOG]

cloacal

Human beings only have an embryonic cloaca, which is split up into separate tracts during the development of the urinary and reproductive organs

hindgut endoderm and proctodeal ectoderm.

Common chamber into which the intestines and excretory system opens. Arises during development in all vertebrates, but in many it becomes subdivided, lost or incorporated into other structures

adding df link to embryonic cloaca leads to a cycle in uberon-simple, as cloaca is a suberclass of embryonic cloaca

uberon

vent

cloacal chamber

UBERON:0000162

http://purl.obolibrary.org/obo/NCBITaxon_9369